The default speed for all motors, motor groups and drivetrains is 50 rpm (assuming gear cartridge is correctly configured).
To change the speed of motors in Python, you follow the same pattern as I explained in your topic from a few days ago.
either, set the velocity for commands that do not include a velocity.
Arms.set_velocity(100, RPM)
or better, just specify in the command.
Arms.spin_for(FORWARD, 360, DEGREES, 100, RPM )
If you fire up the Python REPL, it’s easy to play with these commands and see what options you have.