It is unlikely settings were changed, by you or by an update. This behavior, AFAIK, is not something you can alter or customize, even with registry edits.
This is likely a temporary bug. Try to gracefully restart Explorer.exe to solve the problem without a reboot.
Open up a command window with administrative privileges
Paste each line below, one at a time, followed by enter
taskkill /f /IM explorer.exe
explorer.exe
exit
If this doesn't solve the problem, try rebooting.
If rebooting doesn't handle it, use system restore to bring the system back to a date prior to the problem startingstart date.