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.