Samsung Galaxy S4 Active - phone doesnt lock with side button

[TKBMy03]

I am a super newbie but I have searched and searched and I cant find an answer so I am hoping you all can help. Can you please tell me how to lock my phone. I have thrown it in my purse 3 times and each time I have crank called someone not knowing. I am sure its a simple fix but I am lost. My old S2 was just the side button, but maybe I have another feature turned on that I am unaware of.

Second Question: (which I replied in in another thread) was that sometimes I cant get the phone to wake up. Noticed it last night and wondering if there is something I am not doing or again a feature I have on that I shouldn't.

Thanks for your help and dont flame me if I did this wrong! Like I said - super newbie - forum virgin!!

 

[B. Diddy]

Welcome to Android Central! Go to Settings>Security​, and make sure "Power button instantly locks" is checked on. Do you have that selection?

 

[TKBMy03]

I dont have that setting on my security screen?

 

[B. Diddy]

Sorry, Samsung menus are different from Nexus devices. See this support page: Can I Customize my Samsung Galaxy S® 4 Lock Screen? Which Features can I Access When the Device is Locked? : Verizon Wireless Cell Phones | Samsung

Go to Menu>Settings>My Device>Lock Screen, and select Lock Instantly with Power Key.

 

[TKBMy03]

Oh B. Diddy - you are going to love me. I have ATT and I can get through to the last step but I have no "Lock Instantly with Power Key". Any suggestions on the wake up problem I am having also?