Under my login account there are 3 companies. How do I get a separate username/ password for one of them that needs to be transferred to another person

I've got the steps in transferring one company to another person, troy34.

To transfer, you need to add the user first. Please follow the steps below:

1. Go to Settings, then select Manage users.
2. Click Add user, then enter the user’s name and email address.
3. Select the Roles dropdown, then choose the role you want to assign to the user and hit Send invitation.

Then, assign the user as the new primary admin. Refer to the steps below:

1. Sign in to QuickBooks Online as the current primary admin. 
2. Click Settings and select Manage users.
3. Locate the user you want to make as primary admin.
4. In the User Type column, make sure they're listed as Admin. If not, select Edit to change their role to admin.
5. Select the small arrow ▼ in the Action section. Then, select Make primary admin.
6. Select Make primary admin again to confirm the change, then Sign out of QuickBooks.

When the user gets the invitation email, ask them to select the link and accept the invitation.

You can also remove yourself as a user.

Moreover, I'll drop this article to help you track future transactions from your customers: Add and manage customers in QuickBooks Online.

Hit reply if you need further assistance in managing your company. I'm here to assist you. Have a great day!