Dimtri,
If you have not already done so. please check the note - 2123631.
Also what is the default minimum authorization period you have defined? I suspect it is 1 month which why look back period is restricted to 1 month for every users.
Another suggestion I have is that rather than changing a role, create two roles and IDs, one with 1 month period and another with *. This will make comparison easier and also help you check if your customization is working properly.
Regards,
Shivraj Singh