LevelOne NVR-0104 - Manual (Page 129)

NVR-0104 User Manual 129
Use the "Up" and "Down" buttons on the remote to select a channel on
the "Channel List" and press the "ENTER" button on the remote to
make the selection. Alternatively, if a USB mouse is connected to the
NVR, you can use the mouse and move the cursor to a channel and
left-click to make the selection.