If you have changed your login information for a website in your profile at the website in question, you select the web account in the Zequr dropdown list 'My websites'. Zequr will then go to the login page and insert the OLD login credentials, and all you have to do is to manually overwrite the old credentials with the NEW ones, click on the login button and select 'Finish' then Zequr will offer to remember your new credentials. You can also select Manage websites/Edit websites in the Zequr menu