[Descant]

My familiarity with pontoons is limited to a couple of rentals. There was never any desire to trim up or down. On my planing hull, I trim up or down to adjust the angle of attack for improved ride, efficiency, etc. This involves running the tilt motor for only a coupe of seconds at a time. In the above posts, there is never a reference to "trim up". All I could think of is that you store the bot with the engine out of the water, and in shallow conditions run half up/down until reaching deeper water, at which point, you trim down. In this scenario, I'd guess you return to the dock (trailer?) with the engine half up and the old battery fully charged. Then you raise the engine the rest of the way, engine not running, straining an old battery. On start up you lower half way to get water pick up, start up, and in a minute or two, "trim down", putting a load on the less than fully charged battery. It may be semantics. I think of "raising" and "lowering" the lower unit and "trim" being two different operations, though perhaps controlled by the same button.

Your owners manual Trouble shooting section may address this. It may also suggest reasons to use, or not use, the High Idle button.