Log in to your YouTube account and go to the YouTube Studio page. Click on your user icon in the upper right corner to find the link.

On the Studio page, click on the Subtitles link from the menu items on the left.

Click on a video from your list.

On the Video subtitles page, choose the caption track you want to download and edit. Hover your mouse icon over that track and then click on the Option icon (looks like a vertical column of three dots).

Click Download.

Save the download file on your computer.

Open a text editor. Simple editors work best. On a Windows PC, you can use Notepad. On an Apple computer, you can use TextEdit.

In your text editor, open your file. In Notepad, go the the File and then Open.... Your captions file should be in the downloads folder.

If you are using Notepad, to be sure the captions.sbv file is visible to select, make sure that the options is set to view All Files in the lower right corner of the window.

Double-click on the captions file to open in the text editor.

When you open the file, you'll see that it is divided into sections of text with timestamps.

Edit the text only - correcting grammar mistakes and adding key punctuation. Be careful not to edit the timings, or add or delete spaces between text sections.

Once you are finished, use the text editor's Save command to save the file under its original name and location.

Return the Video list on the Channel subtitles page for the video in YouTube. Click the icon in the Languages column to the right of the video to make the current captions visible.

Click the Options menu (3 vertical dots) in the Subtitles column and select Edit on Classic Studio.

On the edit screen, click the Edit button in the upper right.

Now that editing is enabled, click Actions and then Upload a file in the upper left above the captions text column.

On the Upload a file window that opens, make sure that Subtitles file is selected. Click Browse to find your file on your computer. If you didn't change the file location after editing, it should be in your Downloads folder. Double-click the file to select it.

The name of your file should now appear next to the Browse button. If so, click Upload.

You should now be back on the Transcribe and set timings page. Your updated captions should appear on the left and below the video preview. If everything looks correct, click Save changes, or you can click Delete draft to discard your upload and revert to the state prior to upload.

You'll get a final warning. If ready to proceed, click Publish.

Congratulations! Your new captions are now published with your video.