One of the most common reasons we see for this is that the web browser has stored a previous login and/or password, is automatically filling in that information. Listed below are steps for finding and removing old logins and passwords on most common browsers.
Taken from https://support.google.com/chrome/answer/95606?co=GENIE.Platform%3DDesktop&hl=en&oco=1
Note that the steps listed above are for Windows or Macintosh computers. If you are using an Android phone or tablet, iPad, iPhone, or other simialr device, please visit the Google Chrome Help page at https://support.google.com/chrome/answer/95606?co=GENIE.Platform%3DDesktop&hl=en&oco=1
The site there has options to show these steps specifically for Android phone or tablet, iPad and iPhone.
Taken from https://support.mozilla.org/en-US/kb/password-manager-remember-delete-edit-logins?redirectlocale=en-US&redirectslug=password-manager-remember-delete-change-and-import
You can easily manage the usernames and passwords that Firefox has saved for you.
Taken from https://support.microsoft.com/en-us/help/4028534/microsoft-edge-save-or-forget-passwords
Applies to: Microsoft Edge, Windows 10
When you visit a website that requires you to sign in, Microsoft Edge will ask if you want your user name and password remembered. The next time you visit the site, Microsoft Edge will finish filling in your account info. Password saving is on by default, but here's how to turn it on or off:
Delete previously saved passwords in Microsoft Edge
Taken from https://support.apple.com/guide/safari/passwords-sfri40599/mac
In the Safari app on your Mac, use Passwords preferences to view, add, or edit user names and passwords you saved for websites. To change these preferences, choose Safari > Preferences, then click Passwords.
Due to changes across different versions of Mac OS, we encourage you to use the link listed above to see the most recent version of MacOS, and then use the drop-down menu on the Apple Support page, to select your version of MacOS.
Managing passwords in iOS devices is different enough from desktop Safari, we suggest a separate link:
The link above covers a few different methods for managing passwords on iOS devices. If you need to cahnge or remove a password from your iOS device, please use the link above, and check for your version.