Want to change an estimate but need password? the one I use to open quickbooks doesnt work

Thanks for reaching out to the Community, @mark_lewman.

The estimate may have been created in a closed period that's why it's asking for a password. This also means that a closing date has been set in QuickBooks Online (QBO) for your books to prevent any changes to transactions from before your books are closed.

Please refer to these steps to change the password:

1. In QBO, to the Gear icon at the top right to get to the Account and Settings. 
2. Select the Advanced tab at the left.
3. In the Accounting section, click on the pencil icon.
4. Enter a new password in the Password and Confirm Password fields.
5. Click on Save and then Done.

Once done, you can now proceed with editing the estimate. Here's how:

1. Go to the Sales menu at the left pane to get to the All Sales tab.
2. Locate and select the estimate to open the transaction.
3. Enter the necessary changes, then hit Save and close once done.

For more insights about closing your boos in QBO, check out this article: Close your books in QuickBooks Online.

Please let me know if you have any other questions or concerns by leaving a comment below. I'm more than willing to help. Have a wonderful day!