Adding One Beat

I added a single beat to some measures in a symphonic composition and can't remember how I did it.
The measure shows a +1 in the top right.

Question 2

I am regularly getting corrupted file notifications when trying to download the score to my page online
are there any common reasons for this? It usually reads something like in measure 44 staff 1 was expecting 4/4 but found 11/16. when I go to that measure/staff I usually find an extra rest. I cannot delete it to solve the problem I have to take a picture of it-save the other staves-delete the whole measure all staves-insert one measure-copy the good staves back into the newly inserted staff and then use the picture as guide to copying the corrupted measure/staff in one note at a time.