missing features

M series has less features compared to A series or other upper smartphone of Samsung and 3 finger gesture is not available in any samsung phone , it has palm swipe to capture Screen.

for app lock you can use S secure from galaxy store its Samsung own and for screen shot you can Enable assistant menu, this is best way ,by this option you can also perform other important task such as screen off, navigation, sound, screen rotation, power off menu, notification panel and also specific app option available
To enable assistant menu just go to settings>>accessibility >>interaction and dexterity>>assistant menu>>enable and also click on it and enable>> assistant plus menu

Bro, your device runs on core ui, so obviously very limited features..there is no official way to indicate internet speed on the status bar, so you have to download some 3rd party apps

Now, coming to screenshots stuff..better download and install one hand operation+(very effective and has several useful options/samsung official app)

http://apps.samsung.com/appquery/appDetail.as?appId=com.samsung.android.sidegesturepad

or

go with accessibility option

try redmi it has all .

help me