Where to change the font colour on APP_LOGIN "Save Account" and User Input?

Hi,

I'm now looking for days to change the colour of the font "Save Account" in the Login Window (APP_LOGN) as well as the colour of the input you do in the fields "Account" and "Password". Does anyone have an idea?

In the back of my head my first thought was its hardcoded in the source, I am not sure though.
If you get the GuiEditor in release section you can change APP_LOGIN colors etc.