: Go to Settings > Security and toggle on "Unknown Sources" to allow installations from outside the Play Store.

The final version released with Marshmallow compatibility was v17.34.36 , though it often fails to load content today without manual workarounds. Recommended Access Methods

As of , the official YouTube app no longer supports Android 6.0 Marshmallow . While legacy APKs are available, most users report that opening these older versions results in a "Switch to YouTube.com" prompt or connection errors. Current Status of YouTube on Android 6.0

: Use the links above from APKMirror or Uptodown .