Android Question.

Your phone maybe able to be settings, storage and make your memory stick the primary storage destination for your downloads. Otherwise it will hold that Marshmellow inside it's basic internal memory which is not that great.

 

The only sentence that I actually understand in your post Linda, is the one that says " I appreciate your answers." lol.

 

Did you check for updates?


http://www.androidauthority.com/htc-desire-816-marshmallow-678959/

 

Root it and flash a custom ROM on it. XDA is great:

http://forum.xda-developers.com/desire-816

 

Glad I'm not the only one, Once she stated talking about lollipops and Marshmallows referring to a phone I was lost.

 

^^^this is the answer, but it's easier said than done. You're better off finding a 14 year old who can do it blindfolded

 

The only one who can update your phone to the next operating system is your service provider.Go to settings,about phone,then it will have an option to check for updates.If there are updates available it will tell you and you can download them,if no updates available then you will be stuck on Lollipop.
Only other way to get newer operating system is to Root your phone but it's an intricate process and could brick your phone and probably negate your warranty.
Your data card works in conjunction to your internal storage,not all apps will work if they are on sd card and some things need to be on internal storage.Some things can be moved from internal to sd eg:music,pics,videos but most apps to work properly need to be on internal storage.
Hope this helps.

 

Rooting and unlocking are totally different procedures.If Sprint is not updating that model to Marshmallow and you realy need to have a phone that has the latest operating system on it then you will need to get a different phone.
Go to XDA-Developers web site and see what's involved in rooting,it's not for the faint of heart LOL.