Whenever you change the primary Apple ID password (which seems to be required about every 3-4 months),
You are only forced to change your password every 90 days if you have certain high security application access on your Apple ID account.
At one point I worked for a reseller and had access to Apple Sales Web (a portal for getting sales materials and demo licenses for Apple software), and even though I hadn't accessed it in years, and maybe couldn't anymore, that being attached to my account made me have to change my password every 90 days.
Some older developer accounts can have the issue also.
If you are having to change your password every 90 days, and do not access any internal Apple applications you should open a support case and try to get it escalated until you get someone who can find the right group that has put that on your account and can remove it. Mind you it took me four tries and working with several support groups (Apple Care, Developer Support, etc) before I was escalated to a manager who really took ownership of the case and made sure it got taken care of. Even at that point it took well over a month for it to work its way through the process. But now I have had my same password for 5 or 6 months.
With the number of Apple devices I use at home and at work, it was definitely worth it not to have to update that password on all the services on all those devices 4 times a year.