Welcome as a new member.☺
Exactly how it would be done on a Samsung I don't know, but it's normally as simple as Settings > Battery. On my LG G3, for example, it's Settings > General > Battery. But you should get there easily enough. Nearly always, Screen will top the list of battery usage....that's normal. But the other high users are of interest.
It may also be a good idea to go to Settings > Storage > Cached Data, and clear the cache.
This 'Smart Network Switch' setting may also be relevant to you:
http://forums.androidcentral.com/sa...ung-galaxy-s5-constantly-dropping-wifi-2.html
Get back to us if you still have problems. You may also find more help in the S5 forums, now that you can post there.
Posted via the Android Central App