I contacted the manufacture and asked the purpose of the turn light adjust, here was the response. Pardon the Chinese sellers grammatical errors:
Turn lamp current regulation method: (if prompted to turn light function for charging the battery is already full red, bright green when full.) Has been filled with a battery connected to the output side, it turned red lights potentiometer available.
Hi ronv, so the pot switch out was a fail. The removal of the old pot practically destroyed the contact points to where a new pot/wire could not be soldered. I'm pretty good with soldering, and it was somewhat of a disaster. Ended up not being able to salvage the boost buck as a result. Since I have to do a great many of these, I am thinking this method would be time consuming and frustrating. I don't want to toast any more bucks.