Sticky Targeting - How to turn on/off (PS4)

I'm playing on PS4 with a controller.

A few times recently I've noticed that my target keeps switching automatically. Say I'm targeting monster A and I switch to monster B. Each time I use a skill while targeting monster B my target switches back to monster A. If I switch to another monster C and use a skill again it swaps back to monster A.

I assume I've managed to trigger some sort of "Sticky Targeting" of Monster A. I can see how this would be useful in some circumstances. But at the moment I can't work out how to turn it on and off (I assume I'm accidentally pressing some combination of controller buttons that is turning it on).

Is there a controller combination that turns on/off sticky targeting or is something else happening?

Thanks.

If you have a target active, while holding L2/R2 and you press L1/R1, you will "cycle" target, so switch, this happens to new players when they have to switch crosshotbar by holding R1 then press up, down, circle..etc... or by simply switching crosshotbar by pressing R1

You may also be pressing, left or right without holding L2/R2, by doing so you switch targets

I think this is your case, if it is not..i can tthink of any other things atm

It's referred to as soft targeting (casting a single skill on a target, then going back to your main target) and hard targeting (changing your main target).

When you cycle with left/right based on your current target filter, up/down through your party list, or L1 + up/down through your enemy list, that starts off by soft targeting each person or mob as you're cycling through. To hard target one of them, confirm the selection with the X button before using a skill on it.