Omni 3 GPS buoy Loiter Mode Mission

I am currently developing an automated buoy, with a Pixhawk controller I am using three T200 Thruster motors using the Omni 3 layout.
The problem is this, I want to establish a mission in which the buoy reaches a point and stays in that place no matter what, with a pressure of less than 0.5 meters. The Loiter Radius and WP Loiter variables. When starting the mission, the buoy sometimes does not orient itself in the best way, or when it reaches the point it does not remain, in the waypoints part I use the “Louter Unlimit” but it has a very large area, the value changes but On the map it continues in the same way. What things can I change? What variables can I configure? I look forward to your comments, thank you very much for your time. I’m new to using the Mission Planner.