I had something very similar.
My Objective Tracker (where we see details of what quest we’re on, etc.) kept getting moved to top left of screen upon every log-in.
I solved it by moving the Objective Tracker very slightly away from the Action Bar that it was snuggled up against and then saving. My theory is that you have to find the two ‘guilty parties’ and separate them.
I’m pretty sure that it’s a glitch in Edit Mode that only occurs when you put UI element ‘X’ directly adjacent to UI element ‘Y’ in a very particular position on screen. Hard to reproduce but very annoying for the people affected by it.
Hope this helps.