If the top button on the MOUC3915 monitor (used to switch between display modes like extended screen) stops working, please try to solve the issue as follows:
Disconnect all cables from the dock to the computer and monitor, wait 5 minutes, then replug all cables from the dock and everything should be back to normal.
This method successfully restored the button's functionality. It is suspected that the issue was caused by a newly connected keyboard, as the problem started at the same time the keyboard was plugged in. The keyboard may be interfering with the operation of the monitor.
For anyone experiencing a similar issue, this quick fix is worth trying before assuming hardware failure or contacting support.
