Samsung TV input selection

Samsung TV (6 year old) remote control does not provide a way to directly select an input. Instead, it provides a source button which can be toggled to cycle thru various inputs. The specific actions for a samsung tv that may be configured only lets you select an input. It does not provide a way to emul;ate the source button on the remote control. As a result, I can’t make an input work for an activity. Any suggestions.