Hi accountsmackay,

Thanks for joining the thread!

We can turn off an option on your QuickBooks settings to manually categorise your transactions or match it to an existing transaction. Here's how:

1. Go to Transactions and select Bank transactions.
2. Click on the Gear icon ⚙ and untick Enable suggested categorisation.

For more detailed information, you can check this article: Find, categorise, and edit transactions in QuickBooks Online. 

Feel free to drop a comment below if you have any other questions. Have a nice day!