Wifi connection issues with S5

[AC Question]

Since upgrading to lollipop 5.0 os, my Galaxy S5 Wifi keeps turning on without my command. I've unchecked all smartphone settings but it keeps happening everywhere I go. I contacted T-Mobile & Samsung who asked me to place my phone on "save mode", and it stopped doing it. They suspect it is due to a 3rd party app but unable to tell which one. I can't delete them all as I only have what I need and use. Any ideas?