How do I change my manjaro theme?

Re: Changing default theme – Cinnamon

In Cinnamon you just click the menu button and on the very left see a row of icons. One of them is the system settings. There is a system settings application somewhere in the menus in Gnome, probably in the system cathegory, too. From there you can manage themes and much more.

How do I apply a theme in Linux?

If you’d rather install the theme system-wide so everyone can use it, place the theme folder in /usr/share/themes. Open your desktop environment’s settings. Look for the Appearance or Themes option. If you’re on GNOME, you’ll need to install gnome-tweak-tool.