Cloud edition.
I have removed my custom theme from the Form Defaults in the Payment and Receipts tabs, but when I process uncategorized transactions the custom theme still is selected. There doesn’t seem to be a place to remove the option here.
I’m not sure what you mean by ‘here’ as in the screenshot you’ve posted the Custom theme’s tickbox is still ticked so you’ll have to untick it.
I assume that these unprocessed once already existed before you changed the Form Defaults settings? If so then these existing ones will still have the old default settings. When creating new receipts and payments then the custom theme should not be selected anymore as per your new default setting.
I think that may be the issue. I’ll re-check it when I next import a bank statement.