Upgraded now my images are showing up too small

I recently backed up my blog and upgraded to the latest version. I tried to write a post afterwards and the pictures are way smaller than they used to be. I checked the Media settings to see what they said. They were 150 for thumbnails, 300 for medium and 1024 for largest. I switched it to 800 for medium and 500 for thumbnails and still they are so small compared to what they used to be. I’m not sure what I need to do to correct the problem. The blog posts I had before I upgraded are still nice and large. It’s just the new posts that I’ve created since the upgrade that are showing images much too small.

Any ideas on what I should do to fix this?