I posted this in Apple´s support fora, but I doubt I´ll ever get an answer over there. Besides, you guys are the best

I think there's a bug when programming the Smart Mailboxes. The settings change and are ignored.
They keep ignoring my settings and reverting to random parameters. For instance, if I create one like this:

I save it and when I open it to check, it changes to this:

If I create one like this:

I save it and when I open it to check, it changes to this:

The first number, no matter what I do, ALWAYS changes to 7 after I saved it.
Sometimes it changes from "days" to "years" on its own.
Is anyone else seeing this?
Thank you for your help.
iMac, OS X Yosemite (10.10)