Deja-dup (now Ubuntu Backup) is just a GUI for duplicity, therefore it should store the config files somewhere. I would like to changed the backup volume size to something like 300MB and the increase the --full-if-older-than variable. is this possible?
This has changed in various Déjà Dup versions, but I believe it is currently at:
What can't you change using the GUI front-end?
The settings used to be stored there, and the files are still present.
In more recent version they are stored in:
The deja-dup settings can also be changed with