I'm not sure I understand what's going on here, since I create a virtual environment and it seems to be using the "all users" installation, but whenever I update pip, it does so in a user-specific folder?
I've just installed the latest Python version (using the Windows installer from python.org). I carefully selected the custom installation option and selected to add Python to environment variables and "install for all users", so I saw how the default user folder changed to C:\Program Files\Python39, as seen here:

Then I tried to update pip (from version 21.1.1 to 21.1.2) so I ran python -m pip install --upgrade pip and got this message:
Defaulting to user installation because normal site-packages is not writeable Requirement already satisfied: pip in c:\program files\python39\lib\site-packages (21.1.1) Collecting pip Using cached pip-21.1.2-py3-none-any.whl (1.5 MB) Installing collected packages: pip WARNING: The scripts pip.exe, pip3.9.exe and pip3.exe are installed in 'C:\Users\Currentuser\AppData\Roaming\Python\Python39\Scripts' which is not on PATH. Consider adding this directory to PATH or, if you prefer to suppress this warning, use --no-warn-script-location. Successfully installed pip-21.1.2 WARNING: You are using pip version 21.1.1; however, version 21.1.2 is available. You should consider upgrading via the 'C:\Program Files\Python39\python.exe -m pip install --upgrade pip' command.
So what's with this C:\Users\Currentuser\AppData\Roaming\Python\Python39 folder?
If I run pip --version` I get:
pip 21.1.2 from C:\Users\Currentuser\AppData\Roaming\Python\Python39\site-packages\pip (python 3.9)
So it looks like it has created a user-only installation in C:\Users\Currentuser\AppData\Roaming\Python\Python39?
The problem is that now I have 2 versions, and venv uses the old one. I created a C:\Users\Currentuser\Desktop\test folder and then created a virtual environment within it. In this environment, pip list shows me it uses the old pip version:
Package Version
---------- -------
pip 21.1.1
setuptools 56.0.0
WARNING: You are using pip version 21.1.1; however, version 21.1.2 is available.
You should consider upgrading via the 'c:\users\currentuser\desktop\test\my-venv\scripts\python.exe -m pip install --upgrade pip' command.
So how do I prevent Python from using this C:\Users\Currentuser\AppData\Roaming\Python\Python39 folder and force it to use the C:\Program Files\Python39\ I installed to?