One company file opens but then is totally frozen.

This is unusual behavior, Betsy-in-PDX. 

I appreciate all the steps you've performed to get this resolved.

Since the issue persists, try opening the other files. If you can't, I'd recommend updating QuickBooks Desktop to the latest release to resolve this.

If the problem continues, let's try uninstalling and reinstalling the program. Before doing so, have your QuickBooks Desktop download file (or installation CD) and license numbers ready.

Here's how to uninstall:

1. Close QuickBooks.
2. Go to the Finder menu, then select Applications.
3. Drag the QuickBooks icon to the Trash.

After that, reinstall the latest version:

1. Go to QuickBooks Product Updates.
2. Select your QuickBooks Desktop version.
3. Click Download to download the installer file to your computer.
4. Double-click the downloaded .dmg file.
5. Drag the QuickBooks Desktop icon to the Applications folder to install. Then, restore your company file in QuickBooks.

You can verify the update by pressing the Cmd+1.

If none of these fixes the problem, let's reinstall the program using a clean install. This removes QuickBooks with the installation files that were left behind.

Additionally, I encourage saving a backup of your file. This way, you can restore your company data and continue working.

Please keep me posted if you need additional help with the process. I want to make sure you successfully access your file.

I have 4 "companies"  (bank accounts) that are tracked in QB.  Three of them open but now apparently one has a different password.  Due to computer crashes, new computers, and life in a whirl, I've lost lists of passwords, and also the 2020 QB for Mac model or product #, so I'm unable to get a new password. 

Would I be able to identify myself sufficiently to you via a phone call or via this or an encrypted mode, so that you could tract down my account and help me get a new password?  

Good afternoon, @Betsy-in-PDX. 

I appreciate you joining back in and letting us more about your situation. 

Based on the details you shared, the best route would be to contact our support team for further assistance. They'll be able to review your account on their end and help you out. 

Use this link to get in touch with them: Contact QuickBooks Desktop for Mac. 

Keep us updated on how it goes. I'm only a post away if you need me again. Happy Friday!