Hi @Janeknutson.

I can share some insights to merge two separate accounts. This prompt message will appear when the accounts have a different account type, or the detail type are not related.

To combine two different account names, ensure that you save the accounts under the same account type and tax form section (detail type). This way, you can combine two different accounts. You can reference this article for the detailed steps and information: Merge duplicate accounts, customers, and vendors in QuickBooks Online.  Take a look at the screenshots below for visual guide: 
 

However, if you're using QuickBooks Desktop, ensure that the Account Type is the same as the account you want to merge. This way, you'll be able to edit and change the account name and combine it successfully. For more details, take a look at this article: Merge list entries in QuickBooks Desktop. Please see sample snippets below where I merge account B to A. Edited B's account type to Bank and named it A to combine the account:

Additionally, you'd like to see QuickBooks Online data or review QuickBooks Desktop reports after merging the accounts.

Please let me know if you have other concerns with merging accounts in your chart of accounts. I'm always available to help you out. Take care!