Sorry for the delay in answering.
1) The language switcher on the top header area is just an example, that you can use such feature like language switcher.
You can change the content of this area in Appearance > Widgets > Place in header top bar area.
Please read WPML plugin documentation – https://wpml.org/documentation/getting-started-guide/language-setup/language-switcher-options/
2) Theme Options > Typography. If this doesn’t work, provide screenshots and temporary wp-admin access. Lightshot Screenshot tool https://app.prntscr.com/en/index.html makes screenshots and generates links then you can provide links of screenshots here.
3) We need temporary wp-admin access, to take a closer look.
4) Add the next code in Theme Options > Custom CSS > Global custom CSS:
