Hello! I was wondering if I could switch classes. I don't want to keep switching, just stay a merchant permanately. Is there any way I could do that?

Yes. If you have not used your free class changes, you can do that by going to Preferences, Character Class, and choosing which to switch to. You have four free changes, and once you have used those changes, you have the option to purchase class change tokens. These can be purchased from the Credit shop, or from other users who have stocked the item to their merchant shop. The item names are Merchant Class Token and Rancher Class Token.

Thanks! I'll change my class now :3