Best way to configure

What is the best way to configure daily backups, with grooming, to a large external drive?

I have been having problems with the automatic consolidation when the box was ticked to create a new backup archive after so many increments. It seems to not get rid of the old archives.

I just did not want to only have 1 full image and a crapload of increments, or is that the best way to do it?

I just want the drive to fill up, and then groom. With multiple full images.

I know there is a tickbox to delete oldest backup when the room has run out, but this only applies to the 'secure zone' which I have had other issues with.

I am also having username/password errors while running a backup after logging out of the main user account, into another user account and then back again.

Is this software flawed, or am I doing something wrong?