You can easily change the pre-set size. In the menu bar choose VIEW. Then PREFERENCES. Then THEME. Depending on the theme (i.e. template) you are using, you can change SMALL COVER SIZE here - I certainly can using the a modified version of the 'Crisp' theme. This is the easy way - there are other options if you want to edit your template with DAXEDIT.....

Hope this helps!