Generate captions on resized videos?

i like the video generate caption feature which shows "caption video" under Express main page, but it has some problems:

1. it only generates it once when i upload the video,   if i accidently delete the caption after i opened the main editng panal, there is no way to retrieve it so i have to start all over again from uploading.
2. problem 2: if i resize the video after open it editing panal (after the caption is generated), the caption size will be way to small if the origial size is from wide screen to vertical screen.   should i edit it sentence by sentence? i can't enlarge them when these captions are all grouped for some long sentences will be cut off from the screen.

please help, thank you