Tightening is not the answer Euro, as mine didn’t fall out, I had thread locked them in (low strength), they both split in the middle, leaving half the thread still in place. I replaced that with a metal washed & bolt, after clearing the remains of the old one out, which has held the visor in place even after the 2nd plastic bolt split.
My opinion is use a low strength threadlock and only tighten the plastic bolts up just enough to stop the visor moving, as I believe the flex in the visor cause the plastic bolts to ‘pop’.