Check the input shortcut configuration. Open DDM, go to the Input Controller tab. You can define a shortcut key to quickly switch to a favorite input and another to toggle between two inputs.
- Verify the shortcut keys are assigned in the DDM Input Controller settings.
- Ensure DDM is installed on the computer you are currently using to try and switch. DDM can control input switching from any PC connected to the monitor.
- Check the video and USB upstream port assignments if you're using the KVM function. Each PC (PC1-PC3) needs both a Video Input Port and a USB Upstream Port selected.
If that didn't work: The communication channel (DDC/CI) may be blocked. Ensure no cheap cable extenders or converters are in use. Update graphics drivers on the PC where DDM is running.
Heads up: DDM communicates with your monitor even when the monitor is displaying video from another computer. You can install it on your primary PC to control switching.