“My phone goes quickly into "inert" mode as always have to slide the unlock icon from left to right to use it”
The “inert” mode as you call it is the lock screen. It has a set timer that you change.
The button on the left which you press and drag right unlocks you screen.
The button on the right will turn off all sounds. (like if you are in a meeting or going to sleep)
Press button (icon) on right and slide left. It will say sound off. To turn sound on Press button (icon) on right and slide left.
To change time on your lock screen timer
Press Menu….bottom left button
Press Screen timeout
Press time you want….2 minutes is good, I like 10 minutes and I’ll tell you why. I hate the screen going out when I’m doing something. And if I’m done and want to put the phone in my pocket I just hit the power button for 1 second, that will turn screen off.
Have fun and you are going to be an expert when we are done.