Remove the 3 bed leveling screws one at a time. Put Medium strength Blue Loctite (thread locker) on each screw and put them back in. Then level the bed and it will stay put for a long time. The screws can still turn easy enough to be adjusted when necessary.
Mine has stayed put for at least 6 months now

Do Not use Red hi strength or you'll need a blow torch to get them out.
Hope this helps, Rick