Re: us marine shifter
Most shifters are capable of either push or pull for both shift and throttle. Some of them hae two sets of levers sticking out, (this would be the back side of the shift lever) Others, the cables attach inside the back cover. (attaching points are hidden)
You will have to remove the shift/throttle assembly from the side of the boat so that you can access the cables where they attach to the shifter and move the throttle cable ONLY. If you move them both, you will reverse your shifting. To find out which of the other attaching arms is the throttle, move the shift lever. the one that moves first is the shift arm. USE THE OTHER ONE.
To get the shifter assy off you have to remove the shift arm, the cover plate below that, then you will see the screws that hold the box to the rear of the side panel.