I want to change the font in the login screen - where is the configuration for that?
You can try the method mentioned here: https://askubuntu.com/a/224060. This command will complain "No protocol specified" but should work (omit exclamation mark in the end of the command). Though it changes only the font of the top panel in greeter.
Also you can get the list of other settings which can be adjusted with this method:
sudo -u lightdm dbus-launch gsettings list-keys com.canonical.unity-greeter
Start by opening up a terminal, start typing "terminal" in your unity dash to see the option or press ctrl+alt+t
Lets go to the correct directory:
Now lets make a backup of the file before we make any changes:
sudo cp unity-greeter.conf unity-greeter.conf.bak
Now we need to open up this file and see whats changed, type/copy this:
gksu gedit /etc/lightdm/unity-greeter.conf
The file should look like below:
# # background = Background file to use, either an image path or a color (e.g. #772953) # logo = Logo file to use # theme-name = GTK+ theme to use # font-name = Font to use # xft-antialias = Whether to antialias Xft fonts (true or false) # xft-dpi = Resolution for Xft in dots per inch (e.g. 96) # xft-hintstyle = What degree of hinting to use (hintnone, hintslight, hintmedium, or hintfull) # xft-rgba = Type of subpixel antialiasing (none, rgb, bgr, vrgb or vbgr) # [greeter] background=/usr/share/backgrounds/warty-final-ubuntu.png logo=/usr/share/unity-greeter/logo.png theme-name=Ambiance icon-theme-name=ubuntu-mono-dark font-name=Ubuntu 11 xft-antialias=true xft-dpi=96 xft-hintstyle=hintslight xft-rgba=rgb
Then save and log out.
In case you want to customize your Display manager lightdm may not be the ideal choice. I would replace it with mdm (themability, graphical configuration tools, etc) , which is a bit more bloated but you won't notice any difference except it's running on a 12 year old notebook. Instructions to do so can be found here: How can I replace LightDM with MDM?