Why does quickbooks online use the email address of a company A,for verification when I am trying to sign into company B

Hi there, @david-evelyn.

I can share with you some insights about account verification when signing in to your QuickBooks Online account.

This happens if the two accounts have the same login credentials. If not, make sure to input the correct User ID (email) and Password on the Sign In page.

Here's how:

1. Open this link: https://c70.qbo.intuit.com/qbo70/login?&useNeo=true.
2. Input the correct User ID and Password.
3. Click on Sign in.
4. If QuickBooks needs a verification code, it will be sent to the email you've entered on the User ID section. (In some cases it's the phone number linked to your account).

For more tips about managing your QuickBooks Online account, I recommend checking out the topics from this article: Account management gathers topics for your Intuit Account.

If you have any other questions about account verification, please let me know by adding a comment below. I'm more than happy to help. Have a good one!