How to change File Manager layout (at least favicon)?

I have difficulties in understanding the general Themes/Branding/Styles-structure in WHM/cPAnel on the directory levels, but I was able to clone a style within the x3-Theme and customize it to match with our brand by changing - Login-Site - Header - Logo - Favicon Since my users sometimes need to access File Manager, I would like to customize the appropriate Theme or Style as well, at least the favicon. I haven't yet found out how and where I can do this. Any idea, anybody? Thank you! Sascha PS: I also wonder how to change the browser-title for the login-page? I have already changed the favicon & logo there, but can't find the appropriate file to change the title "cPanel Login"?