Help How to root and install Custom ROM for GT-I9505

[Best_Striker]

Version:
AP: I9505XXUHPK2
CP: I9505XXUHPK2
CSC: I9505OJVHQB1

This is a used phone I bought from someone, but I am not really happy with android version 5 and want to install a custom ROM. I'm not certain where to begin looking for guides or which Custom ROM is the latest to install. I had bad experiences following tutorials for previous phones I had which messed up the previous phone I had. I just want to know where I can begin? Should I first try rooting my phone, then try installing a custom ROM? Is there tutorials on how to do so? Any help would be appreciated

 

[dontpanicbobby]

What don't you like about the Samsung Galaxy S4? j/c.

 

[Best_Striker]

What don't you like about it? j/c.

Well I'm getting weird glitches from time to time, and apps not having enough space on my internal memory. Glitches like apps never being set as my default app even though I said 'always use this app'

 

[dontpanicbobby]

The 16GB internal model? Clear the cache and uninstall some of the apps you don't use anymore or the person you bought it from used and you don't. Those old apps eat up much internal memory.