I don't know about the checkboxes Kathy, but if you want to change 'Model' to 'Class' (I'm presuming you mean Product Model?), then all you need to do is carry out a search and replace in your Zencart folder for the word you need and simply change each instance of 'Model' to 'Class'. I did a quick search through a 1.39h version and there were 47 instances to change. Some of these may be unnecessary because they relate to 'document products' etc but it's easy to make the changes.