Why are my wallpaper settings, tile, zoom, center, scale, fill or span options no longer available?

These options are removed from the default GUI wallpaper settings (accessible from the Settings application) in the recent versions of GNOME 3 for some reason.

As an alternative, you may use another GUI application called (GNOME) Tweaks to get those extra options. To install it first run

sudo apt install gnome-tweaks

Then launch Tweaks and go to the 'Appearance' section on Ubuntu 18.04 and later (or the 'Desktop' section on Ubuntu 17.10). You'll get options to adjust the background and lock screen images.

On Ubuntu 18.04 and later, the settings can be found under Tweak's 'Appearance' tab (instead of 'Desktop').

You can use a terminal tool called gsettings.

• gsettings list-schemas -- among others you will get,

  org.gnome.desktop.background : Option 1

  org.gnome.desktop.screensaver ( for lockscreen, just in case ) : Option 2

• gsettings list-recursively org.gnome.desktop.background, must try!

  You will what different options are supported by the schemas with there default values, you'll get something like this,

  org.gnome.desktop.background picture-options 'zoom'
  

  now if you want to know what are the other values supported by the options, other than default, do, for example.,

• gsettings range org.gnome.desktop.background picture-options

  And voilà:

  • 'none' (blank screen/ color black),
  • 'wallpaper',
  • 'centered',
  • 'scaled',
  • 'stretched',
  • 'zoom',
  • 'spanned'.