Galaxy S4: Anyone have problems using other apps while on the phone??

[owensch1]

While making phone calls I cannot push the back button or the home key to me able to use other apps while I'm talking on the phone. The only workaround is to quickly switch to my homescreen RIGHT after connecting to a call. Before I could switch at any point. There is several times where I need to look at an old email or text or something while talking to someone but I can't and it's super frustrating. Anyone have a solution?

Sent from my m'fn Galaxy Note son!