Step 1: Make sure your phone has unknown sources checked in settings, to do so go to setting>personal>security>device administration>unknown sources

Step 2: Download and install xposed installer, Download exposed installer from here: [ Register or Signin to view external links. ]

Step 3: Open Xposed installer, tap framework, tap install/update, once done installing it will ask you to reboot, reboot your phone

Step 4: Once the device is back on open Xposed installer, go to download and look for or type in the search bar, YouTube AdAway, install the latest version, go back to main screen of Xposed installer and tap modules, tap the box next to youtube adaway, a check mark should appear, it will ask you to reboot, reboot your phone

Step 5: Once your phone is back on go to youtube and enjoy adfree videos

Note: Every time the youtube app updates you must return to exposed installer and update youtube adaway aswell, they usually take a few hours after the app updates to put out and update for adaway!