Thank you for your post.
FileMaker Server will not allow a backup schedule of more than 7 days. The maximum is 7 days. If you try to enter a number larger than 7, it will revert to 7.
However, in your instance, you are saying it is reverting to 1. I cannot duplicate the problem with either FileMaker Server 9 or FileMaker Server 10.
If you can let me know what steps you took, I will try to duplicate it here.
It appears you want a longer backup schedule, so I would suggest entering this as a feature request at:
I know I could easily copy your suggestion and paste it into the web form, but there are additional questions asked that only you can answer.