How to revert back from Marshmallow 6 to Lollipop 5 in Samsung Note 4? My Samsung Note 4 is updated to 6, but I don't like it and I want to go back to Lollipop. Is it possible to do it easily?

I heard that there are many problems with 6.
Unfortunatelly the downgrade isn't so easy at all.

You have to download a proper official Samsung Galaxy Note 4 Lollipop system image from SamFirmware and install it from Odin (or Heimdall on OS X). You have to read about this process before you do anything (eg.: enable developer options, USB debugging, etc)

It will be a clean install so if you have any important app or app-data you should backup all of them (I prefer TitaniumBackup Pro, but you have to be rooted.) with Kies (if you aren't rooted).

If you stuck there is a guide for a Samsung Galaxy S6.