diff --git a/src/App.jsx b/src/App.jsx
index 215c327f..804a45b6 100644
--- a/src/App.jsx
+++ b/src/App.jsx
@@ -178,6 +178,8 @@ const App = memo(() => {
   const durationSafe = duration || 1;
   const zoomedDuration = duration != null ? duration / zoom : undefined;
 
+  const isCustomFormatSelected = fileFormat !== detectedFileFormat;
+
   const firstUpdateRef = useRef(true);
 
   function safeSetConfig(key, value) {
@@ -946,7 +948,7 @@ const App = memo(() => {
         Try one of the following before exporting again:
         <ol>
           {detectedFileFormat === 'mp4' && <li>Change output <b>Format</b> from <b>MP4</b> to <b>MOV</b></li>}
-          <li>Select a different output <b>Format</b> (<b>matroska</b> takes almost everything)</li>
+          <li>Select a different output <b>Format</b> (<b>matroska</b> and <b>mp4</b> support most codecs)</li>
           <li>Exclude unnecessary <b>Tracks</b></li>
           <li>Try both <b>Normal cut</b> and <b>Keyframe cut</b></li>
           <li>Set a different <b>Working directory</b></li>
@@ -956,9 +958,9 @@ const App = memo(() => {
       </div>
     );
 
-    const { value } = await ReactSwal.fire({ title: i18n.t('Unable to export this file'), html, timer: null, showConfirmButton: true, showCancelButton: true, confirmButtonText: i18n.t('OK'), cancelButtonText: i18n.t('Report') });
+    const { value } = await ReactSwal.fire({ title: i18n.t('Unable to export this file'), html, timer: null, showConfirmButton: true, showCancelButton: true, cancelButtonText: i18n.t('OK'), confirmButtonText: i18n.t('Report'), reverseButtons: true, focusCancel: true });
 
-    if (!value) {
+    if (value) {
       openSendReportDialogWithState(err);
     }
   }, [openSendReportDialogWithState, detectedFileFormat]);
@@ -989,7 +991,7 @@ const App = memo(() => {
         customOutDir,
         filePath,
         outFormat: fileFormat,
-        isOutFormatUserSelected: fileFormat !== detectedFileFormat,
+        isCustomFormatSelected,
         videoDuration: duration,
         rotation: effectiveRotation,
         copyStreamIds,
@@ -1006,6 +1008,8 @@ const App = memo(() => {
         await autoMergeSegments({
           customOutDir,
           sourceFile: filePath,
+          outFormat: fileFormat,
+          isCustomFormatSelected,
           segmentPaths: outFiles,
         });
       }
@@ -1037,9 +1041,9 @@ const App = memo(() => {
     }
   }, [
     effectiveRotation, outSegments, handleCutFailed,
-    working, duration, filePath, keyframeCut, detectedFileFormat,
+    working, duration, filePath, keyframeCut,
     autoMerge, customOutDir, fileFormat, haveInvalidSegs, copyStreamIds, numStreamsToCopy,
-    exportExtraStreams, nonCopiedExtraStreams, outputDir, shortestFlag,
+    exportExtraStreams, nonCopiedExtraStreams, outputDir, shortestFlag, isCustomFormatSelected,
   ]);
 
   const capture = useCallback(async () => {
diff --git a/src/StreamsSelector.jsx b/src/StreamsSelector.jsx
index 8d174f7d..bd289a6b 100644
--- a/src/StreamsSelector.jsx
+++ b/src/StreamsSelector.jsx
@@ -152,10 +152,10 @@ const StreamsSelector = memo(({
         </tbody>
       </table>
 
-      {externalFilesEntries.length > 0 && !areWeCutting && (
+      {externalFilesEntries.length > 0 && (
         <div style={{ margin: '10px 0' }}>
           <div>
-            {t('If the streams have different length, do you want to make the combined output file as long as the longest stream or the shortest stream?')}
+            {t('When tracks have different lengths, do you want to make the output file as long as the longest or the shortest track?')}
           </div>
           <SegmentedControl
             options={[{ label: t('Longest'), value: 'longest' }, { label: t('Shortest'), value: 'shortest' }]}
diff --git a/src/ffmpeg.js b/src/ffmpeg.js
index 8932ceea..826c1bc5 100644
--- a/src/ffmpeg.js
+++ b/src/ffmpeg.js
@@ -255,9 +255,13 @@ async function cut({
   await transferTimestamps(filePath, outPath);
 }
 
+function getOutFileExtension({ isCustomFormatSelected, outFormat, filePath }) {
+  return isCustomFormatSelected ? `.${getExtensionForFormat(outFormat)}` : extname(filePath);
+}
+
 export async function cutMultiple({
   customOutDir, filePath, segments: segmentsUnsorted, videoDuration, rotation,
-  onProgress, keyframeCut, copyStreamIds, outFormat, isOutFormatUserSelected,
+  onProgress, keyframeCut, copyStreamIds, outFormat, isCustomFormatSelected,
   appendFfmpegCommandLog, shortestFlag,
 }) {
   const segments = sortBy(segmentsUnsorted, 'cutFrom');
@@ -276,7 +280,7 @@ export async function cutMultiple({
     const cutToStr = formatDuration({ seconds: end, fileNameFriendly: true });
     const segNamePart = name ? `-${filenamify(name)}` : '';
     const cutSpecification = `${cutFromStr}-${cutToStr}${segNamePart}`.substr(0, 200);
-    const ext = isOutFormatUserSelected ? `.${getExtensionForFormat(outFormat)}` : extname(filePath);
+    const ext = getOutFileExtension({ isCustomFormatSelected, outFormat, filePath });
     const fileName = `${cutSpecification}${ext}`;
     const outPath = getOutPath(customOutDir, filePath, fileName);
 
@@ -393,22 +397,27 @@ export async function html5ifyDummy(filePath, outPath) {
   await transferTimestamps(filePath, outPath);
 }
 
-export async function mergeFiles({ paths, outPath, allStreams }) {
+export async function mergeFiles({ paths, outPath, allStreams, outFormat }) {
   console.log('Merging files', { paths }, 'to', outPath);
 
-  // https://blog.yo1.dog/fix-for-ffmpeg-protocol-not-on-whitelist-error-for-urls/
+  // Keep this similar to cut()
   const ffmpegArgs = [
     '-hide_banner',
 
+    // https://blog.yo1.dog/fix-for-ffmpeg-protocol-not-on-whitelist-error-for-urls/
     '-f', 'concat', '-safe', '0', '-protocol_whitelist', 'file,pipe', '-i', '-',
+
     '-c', 'copy',
 
     ...(allStreams ? ['-map', '0'] : []),
     '-map_metadata', '0',
+    // https://video.stackexchange.com/questions/23741/how-to-prevent-ffmpeg-from-dropping-metadata
+    '-movflags', 'use_metadata_tags',
 
     // See https://github.com/mifi/lossless-cut/issues/170
     '-ignore_unknown',
 
+    ...(outFormat ? ['-f', outFormat] : []),
     '-y', outPath,
   ];
 
@@ -428,10 +437,12 @@ export async function mergeFiles({ paths, outPath, allStreams }) {
   console.log(result.stdout);
 }
 
-export async function autoMergeSegments({ customOutDir, sourceFile, segmentPaths }) {
-  const ext = extname(sourceFile);
-  const outPath = getOutPath(customOutDir, sourceFile, `cut-merged-${new Date().getTime()}${ext}`);
-  await mergeFiles({ paths: segmentPaths, outPath });
+export async function autoMergeSegments({ customOutDir, sourceFile, isCustomFormatSelected, outFormat, segmentPaths }) {
+  const ext = getOutFileExtension({ isCustomFormatSelected, outFormat, filePath: sourceFile });
+  const fileName = `cut-merged-${new Date().getTime()}${ext}`;
+  const outPath = getOutPath(customOutDir, sourceFile, fileName);
+
+  await mergeFiles({ paths: segmentPaths, outPath, outFormat, allStreams: true });
   await pMap(segmentPaths, path => fs.unlink(path), { concurrency: 5 });
 }