Redo Credentials every three months? WHY?

I am one of the admins.  All of the admins have all been all over it, along with Tier 2 assistance.  What we are being told by MS is that when you set up the credentials, it creates temporary tokens.  There a couple of settings that are supposed to create tokens that last a year, but acccording to TS, these parrticular tokens expire in 90 days, regardless.  Again, if this is the way it is, loads of folks would have this problem, and TS would know, but they don't.