As a sole trader, should I be scanning invoices from wholesalers where I have credit accounts or just random day to day purchases?

It depends on you on what you'd be scanning, @@tb-electrical-ou.

As long as you hold onto receipts that shows your business expenses. But if you have specific questions about receipts and record-keeping, I'd suggest consulting your accountant. 

If you need to upload your receipts and bills to your QuickBooks Online (QBO) account, check out the Upload your receipts and bills to QuickBooks Online article for the steps and details. 

Let me know if you have further concerns with QuickBooks, I want to make sure all your questions are resolved. I'm also here to provide further assistance whenever you need it.