There are two ways to edit captions for a screen recording you've previously completed. After editing your captions, you will need to re-upload your video file. You will not have to re-record your video, however, so that's great news!
The first way you can edit captions is by uploading a new captions file from the Content area of the website. For more information, see the article about uploading captions.
The second way you can edit captions is from the Video Editing tool.
To open the Video Editor, log into your account.
Click the Open Video Editor icon () at the top of the screen.
On the Content Manager screen, click the video for which you want to edit captions.
Click to display the Captions menu.
Next to the existing captions, click the Edit icon.
Insert your cursor in the Captions Text box, edit the caption text as necessary, and then click OK.
To reupload your video with the edited captions, click Upload to Screencast-O-Matic.
For more information about uploading your videos, you can watch the short tutorial here: https://screencast-o-matic.com/tutorial/upload-to-screencast-o-matic/
Once the video with the new captions is uploaded, you will more than likely want to delete the previous video you uploaded from your account. For more information about how to do this, click here: https://screencast-o-matic.com/tutorial/manage-video-content-in-hosting/
That should do it!