I appreciate you getting back to us, @MDBR.

Since QuickBooks record all payments to the parent account, you'll need to check your bank statement. This way, you'll be able to know the amount of each child account that you're going to enter in the journal entry.

You can also check the balance amount of your child accounts in the Chart of Accounts and Balance Sheet report for your reference. 

You can check out this article for the detailed steps and information in creating journal entry: Create a Journal Entry.

Also, setting up a percentage based on the credit limit for each card isn't available in QuickBooks. But I want to let you know that we're taking note of your feedback and suggestions to improve the experience we're providing.

In case you need tips and related articles in the future, visit our QuickBooks Community help website for reference: QBO Self-help. 

Please feel free to post any questions you have below. The Community is always here to help out.