It's actually fairly simple. Follow these steps:
- Go to Activities > Applications > Add/Remove Software
- Search for: gnome-tweak-tools, install it.
- May not be mandatory Search for: gnome-shell-extension-common, install it.
- May not be mandatory Search for: gnome-shell-extension-alternative-status-menu, install it.
- Log out. Log back in.
- Open the terminal, type: gnome-tweak-tools
- It'll open a window titled 'Advanced Settings'
- Go to 'Shell'
- Where it says 'Arrangement of buttons on title bar', select 'All' from the drop down menu. You now have the minimize, maximize and close buttons in most of your title bars.
You may also choose to only have the 'Minimize and Close button'.
I hope this helped!