I cannot change the clock source in the Lynx Mixer – it keeps reverting back to the previous setting

Clock settings can only be changed when no audio applications or processes are accessing the Lynx card drivers. Close any open audio applications or halt any audio processes that cause the card to be recording or playing before changing clock settings in the Lynx Mixer program.

Alternatively, it is possible to enable clock changes when the driver is active by selecting from the Lynx Mixer: Settings > Advanced > Allow Clock Change if Active.