thumbnail image size


I am trying to make thumbnail size bigger. But more importantly I am trying to control the size of thmbnail images however I want. It was originally at 120x120, being automatically generated from the product details image.

I changed the thumbnail size to 220x220, but didn’t change. After some research, I unchecked "Thumbnail width on product list page (leave empty to use original size) " from the appearance setting page. Then my thumbnail images got bigger.

But when I tried to make bigger, up to 300x300, it didn’t get any bigger.

Is it restricted by something? Do I need to change the code in order to make it truly configurable? If yes, where and how?

thank you in advance!

The setting is in

Administration, Settings, thumbnails

I have the same problem with 2.08