How can I increase the default thumbnail size in WordPress from 150px by 150px to something bigger? I want all my thumbnails to be more around 400 by 400. This is because I am trying to setup a photography blog where you can see the images in nearly full size.
I have tried to change the media settings, but even if I change the values, the thumbnails still display at 150 by 150...
All comments welcome.
Oh, I am running simple gride responsive theme, if that makes any difference (I don't think it does because the 150 x 150 thing seems to be a WordPress default for thumbnais...).