Hi there,
Welcome to the QuickBooks Community. The program is designed to help you simplify the way you categorize your transactions and I'd like to help make sure you experience this benefit without running into issues.
Based on the details you've provided above, I recommend checking to see if you have bank rules enabled. Banking rules is a feature that automatically categorizes your transactions for you. Here's a helpful article that provides more info about: Set up bank rules to categorize online banking transactions in QuickBooks Online. I'm suspecting that you have rules set up that are automatically categorizing your transactions to specific account.
Give this a try and let me know how you make out. I'll be one message away in case you need additional support. Otherwise, I wish you a great rest of the day!