Data backup configuration

Just a small question on data backup. Is it possible to reduce the number of data backups? By default, the minimum before deletion is one week. I would only need a maximum of 3 full backups.
I have not found the config file to modify.
Thanks in advance.

What are you trying to achieve?
You want to do a full backup every night and delete backups older than 3 days?

Yes exactly. I have a usb drive for my backups, and I cannot get more then 3 backups on it.

You should be able to doing by doing this:

config setprop backup-data CleanupOlderThan 3D

After the change, this change will not be preserver by the web interface.

IMHO, this is not the best way to save space. Configure the system to execute an incremental backup, once a week it will perform a full backup, and you will consume much less space!

Thanks for the instruction, and in fact I will merely test your advice. I am usually not very found of incremental backups but if there is a full one every week, it should be fine.
Once again, thank you.