Oh my!It looks as though it is automatically running in HIDPI mode. To fix this, go to Scene -> Project Settings. If you can see it, the pop should appear, and you will want to un-check "use_hidpi_theme", and then restart the program. Let us know if that helps!
Project settings are for the project. You might need to change the editor settings in the top-right corner.Settings->Editor Settings->Global->Hidpi Mode->LoDPI