I had this problem too. Try pulling the bridge of your glasses down a little bit over the top of the mask, that usually helps. Or create a seal at the top as ot

I had this problem too. Try pulling the bridge of your glasses down a little bit over the top of the mask, that usually helps. Or create a seal at the top as other commenters suggested. Also be mindful if you are breathing out through your nose or mouth, it makes a difference depending on how your mask fits.