I’m glad to see Wild Ricochet making a return to Standard; it’s such a fun card, and can lead to hilarious reactions when timed right (A friend of mine once used Wild Ricochet against a Primal Command, spinning two lands back to the opponent’s deck and gaining 14 life). Sadly, it also can lead to some confusion!
First off, Ricochet makes a copy of whatever spell you’re aiming it at. The copy isn’t cast (so things like Blistercoil Weird won’t trigger off of it), it is simply created on the stack under your control. It’s YOUR spell, so you choose targets as you like, just as if you’d cast the spell yourself. So if you Wild Ricochet a Doom Blade, you can’t aim your copy at your opponent’s Hexproof creature, but you CAN aim an Enlarge copy at your own Witchstalker.
Second, and more to the point of this tip’s name, you might be able to change the target of the original spell… but you change it as if you’re the controller. Meaning, you only select from targets that the spell could legally be aimed at in the first place! Meaning that while you can use Ricochet to aim that previously mentioned Doom Blade at your OPPONENT’S Witchstalker (since it’s his Doom Blade, it gets around Hexproof), you won’t be able to double your pleasure or your fun on a Rakdos’s Return. Since RR targets an opponent, you’ll only be able to aim your copy at the original caster; the original spell itself cannot be turned back on its controller, because you are never your own opponent (no matter how badly you might misplay things!). In a multiplayer game, you can aim that RR at a different player, but in a typical 1-vs-1 game, your best bet is to empty their hand and blast them for as much as they blast you.