Bank transactions mistakenly matched with previous customers how should I do? I don’t want to select any customers.

Hi there, 

Welcome to the QuickBooks Community. It's essential you're able to unmatch the bank transactions so they're recorded correctly going forward. 

QuickBooks is designed to help you streamline your accounting using the powerful features offered in the program. In order to unmatch the transactions, I encourage you to check out the following article that shows you how to: Unmatch downloaded bank transactions or move them to another account. From here you can correctly match the transactions using the helpful steps provided in the is article here. 

You're more than welcome to ask questions as you go through the article. I'll be one message away in case you have other questions.