When you commit your code in Studio, the first time Studio will prompt you for credentials and these then get stored in the Windows Credential Manager so that Studio does not prompt you subsequent times when you commit.
Whilst this is handy in many scenarios it causes a royal pain in others, specifically when we have to work on a shared VM as then the commits end up being submitted under the incorrect person.
It appears to be impossible to disable this behaviour, even if I fully disable the Windows Credential Manager Studio still somehow seems to be able to use it and add the credentials.
In most other GIT software you can choose to save your creds or to enter them each time. Please give us that option.