I update my date of birth on my profile, but whenever I try playing games at my age range I get told it's restricted to 18+.

Same here

Same

Dumb question....
Have you tried changing, or setting, your birthday on the MyProfile button?
(I guess you already did that...)
So, what game won't let you play it?
I tried on listed as 18+, after I changed my birth year to 2015, and it let me play.

same here

The problem is that after you input the date information and hit update, it does not update. That makes it impossible for users that haven't input a date to play games restricted to 18+.

Has anyone found a fix for this?

I think I figured it out...after I changed my birthdate, I logged off and logged back in, and now it works. :) Hope this helps someone else.