Some transactions are marked as cash (despite not being cash transactions) and aren't possible to edit. How can I change or edit these entries?

Hello there, marcusdomleo-gma. Let's work together this get this sorted out.

Just to confirm, have you been adding transactions using the Snap receipt option and then uploading the photo in QuickBooks Self-Employed? If you do, those that are showing as Cash are the once that you've manually entered. So, instead of Snap receipt, you've selected the Add expense manually, the same with the Add transaction button in your browser. Please see the screenshots below as your visual reference:

To give you additional information on how to track your income and expenses, please read it through this article: Manually add transactions in QuickBooks Self-Employed.

You can click the Reply button if you need any additional help with recording transactions. I'll be right here to help.