I had to reinstall Ubuntu and then I wanted to restore the backup I saved in Google Drive (using Deja-dup). It didn't ask me which account, it just said that there weren't any backups to restore. After a while, I noticed that the google account it was using was different from the one in which I have my backup, although I didn't choose any account from which restore the backup (it seems that it was using the account with which I logged in in Ubuntu).

Anyway, it looks like there is no way to change this account from the application. Actually, I've seen a lot of similar questions in this site regarding this same issue. In particular, this one has a good answer. It recommends the use of dconf-editor, which I have already downloaded. Unfortunately, this didn't solve the problem, because none of the modifiable settings says anything about the google account deja-dup is using (or maybe I'm just not able to find it?). Can anyone give me a helping hand here?

Available configurable settings in dconf-editor