Highbeams and wiprs

The wiper arms have a spring that is suppost hold the blade to the windshield. If the spring is weakened, which is probably ths case, would certianly cause the problem, also the speed you are going can cause this problem, the way the wind flows over the windshield.

If I understand the problem.
Your passanger side high beam will not work even after you changed the sealbeam,
but when you pull your handle back to flash your lites both beams work on the high beam.
When you push the handle foward to dim lites, the passenger side will not work.

Sounds like your dimmer switch isn' working like it should

Hope this helps
Good luck