GPS River mode - how does this work

Hey I have a 14 SC350....
It's new to me and when I went out two weeks ago we have trouble dialing in the GPS speed.
The river current that day was a little gnarly but not really too bad....
Speed control was reading 23mph and the boat was riding at about 20mph.
Two questions:
1) There is a setting for river mode...but the manual is really vaugue about it. can anyone explain this and do I have to adjust up/down everytime we are switching direction?
Manual: "River Mode: Interactive popup including touch toggle from ON to OFF, and River Flow settings."

2) can i revert the GPS cruise to paddlewheel mode? i had this on my previous boat and the paddlewheel seemed to work well on the river.

Thanks Guys!