I'm happy to learn you're using QuickBooks to streamline your work. QuickBooks offers a variety of apps which help streamline your work. I'd be glad to give you a hand with this.
Based the the description you provided above, I have an idea of what you're experiencing. QuickBooks offers a handy feature called "Auto-recall". Auto-recall uses the information from the last saved transaction of that type for that specific customer, supplier, or employee. The good news is QuickBooks gives you maximum flexibility with this feature as you can turn it off and on at will. Here's how to turn off the feature:
Check out this article for more info on: How to use auto-recall to pre-fill transactions. Give this a try and if you have questions, please leave them in the comments below. I'll be happy to get back to you as soon as possible.