Arrogance or something else?

My girlfriend has a 5 month old Jack Russell. Although she does know her commands, sit, stay, etc. she is literally flawless in our home, with and without my Staffy (Ferris) about. she just won't behave outside. It's not even a matter of her misbehaving because of distractions, or if it is then literally everything is a distraction. She doesn't work great with treats or toys as her favourite toy is whatever Ferris is playing with. It's as if she knows what we want her to do but she can't grasp the concept that it's a command not a request no matter what tone of voice we use.

Any advice is greatly appreciated.

Shes just being ignorant and doing her own thing, to her theres much better things to see and smell and play with than yourself, ruby use to be the same, just takes persistance, I found praisal works very well with ruby and high pitched voices saying good girl come on, lmfaoo sound like a plonker but it worked

Have you tried high value treats on walks only. By high value I mean something ultra tasty like Frankfurter. Use this only when walking.

The first thing I'd say is don't ask too much of her. The more you ask and she ignores you, the more she learns she can ignore you. Try and ask her to do things when you can set her up to do it easily, so for example call her when she's coming anyway, or call Ferris and call her at the same time. That way you can reward her for doing something easy and that will get in both of your minds that it is achievable.

Another option is only to do training work outside when she's on the lead, in less exciting places and on her own to start off with. Get some basics in place in easy circumstances, then go for harder.

As for distractions, yes, everything is a distraction for a 5 month old pup. She's still learning her world. A leaf, twig, or stone can be hugely interesting at that age.

I see what we ask of our animals in terms of requests, not commands. Yes, I want my dogs to do what I ask them when I ask them, and I will sometimes give them an 'oi!' if I'm asking something I know they can do but that they are choosing not to, but what I want most of all is for them to do what I ask willingly and happily, not because I command them to. You want your requests to be clear and easy to understand but you can still do that with a nice tone of voice. Just like us, if you ask nicely it's so much easier to do that if you're feeling forced into something.

I guess, though, that the other thing to remember in this case is that this is a true terrier we're talking about here, and the terrier mindset is to be focused on what's caught their eye at the moment, at which point you're forgotten about. Give me a staffie any day!