Annoying Lock On switch

The switching of lock on targets is notoriously sensitive or unintuitive using a mouse (see here and here, for example).

You can turn off Lock On by pressing F, unless it's mapped differently (obviously). Check your Key Configuration under Controls in the System Menu to be sure.

Unfortunately, the key-binding for 'Switch Lock-on Target to the Left/Right' seems to be fixed to 'Move Camera Left/Right', and changing that is not even an option:

Unfortunately even this answer doesn't actually fix anything. The game automatically switches to whatever is to your Right, so if an enemy is to your right, you will likely lock onto them after locking onto your enemy in front of you, then it will also likely switch back and forth. This is just bad design that cannot actually be corrected completely (even the so called fixes people come with still ultimately do not actually fix the issue, just make one aspect of it, related to the facing direction of your character, and not the actual auto lock switching.

It's very likely just an oversight like not having keyboard and mouse prompts for a long time (they have them now lol).