Happens on Android too and has nothing to do with keeping the settings window open. As I and others mentioned before, it happens when logged in for along time or switching back and forth between devices.
On apple device you have to open settings to swap accounts, IF I Leave the settings window Open in the Background!!! It pops up after awhile. like I said...
If I close the settings window after the account change it does not pop up. Tested Tons! lol
Never with the settings window closed and I play ALL day does that window pop up even when myself and friend swap accounts and devices. weird!
but heh, If you say so! lol
as for android, mine have older software maybe cant do it and has never happened.