Steps to update rooted Galaxy S6 I have a rooted Galaxy S6 on 5.1.1, the first and only version I rooted my device on. I want to update to Marshmallow and still have a rooted phone. What are the steps I need to do to make this happen?
So long as you don't try an OTA (Over The Air update, such as you would be offered with a stock phone), you shouldn't lose root. You just need to choose and flash a new ROM. There are many ROMs you could choose from but I always used Cyanogen Mod on my rooted phones. CM has it's own updater, so you can update with this in future.

Google your options and make sure you follow instructions carefully. With many ROM's you will need to install the Google Store app manually if you want to install apps in the normal way after your update.