Acer KG251Q monitor problem

Hello, the buttons on the monitor itself in this model "Acer KG251Q" stopped working, after a while they started working again (but just for a couple of days), what could be the problem? I would not bother with this question so much, but I will need to connect it to the DVI-Port, but now it works via HDMI and it cannot switch automatically (probably so locked in the settings). Thanks in advance for your answers.