You can have two channels set for priority.
In software, select the channel you wish to be the second priority, go to the atr column, press enter and get the drop down then select B, this now makes this channel the second priority.
Now, select the channel to be the first priority and go to atr and press enter select A and this is now the first priority channel.
This priority selection only works when you have these channels set up in the scan list and scan is turned on.