Some older rigs do do this by design I'm afraid, if this is the case there is no simple solution
Diagnosis procedure,,, Turn off and/or unplug EVERYTHING, including all circuit breakers.
If it still trips the breaker,,,, You have an older rig not wired to modern code
If the GFCI holds, then:
Now, plug in a 120 volt lamp, where you can see it as you sit/stand/lie near the breaker panel.
Turn on just the breaker for the lamp, hopefull the lamp goes on (alternative, use some kind of adapter so you can plug the lamp in to the outlet on the pole)
Turn on breakers one at a time and watch the light,,, when things get kind of dark (Which will happen suddenly) find out what that breaker controls, label it, turn it off, reset the GFCI and continue to turn on the remaining breakers one at a time until you fingure out what circuits have faults.
Often it will be either the hot-water heater or the converter. Sometimes fixing is easy, other times, not