[hider=Arú drafts and scrambled thoughts.]
She can cause change, simple as that, but because the domain is so broad and widespread it would actually be fairly weak unless focused on something, which given the nature of change, is unlikely. It also has specific rules as well, since she can't change anything around her without:
First: there being something to change
Second: an understanding of what it is she's trying to change
And third: an understanding of how to change it so that what happens is what she wants to happen, unless she just doesn't care and just causes a random change.
Also she can't change things on a large scale without tiring herself out, and she has an exponentially harder time changing something the more powerful or complex it is, with things like the psyche or energy being impossible for her to cause change to as each is much too complex and too powerful for her to mess with.
So in a sense it would be like alchemy, requiring clever use of it and a real understanding of something before being able to cause complex or specific changes.
But ironicly, with what I'm thinking for her character, she'd likely be more interested in trying to learn about concepts rather then specified knowledge, as they would be far more flexable, able to connect to one another in interesting and bizarre ways, hastening her ability to make different types of simple changes.
As such her powers to change anything would be kinda weak unless it's of direct relation to her, given how unfocused and spread out they are. She can also reverse change, but the fact that the change had occurred is never undone and it takes her more energy to do so. And if she attempted to try and change something of another god's making without their help, she would probably be wiped for a while, regardless of if it worked.
As the goddess of change though, she would be highly aware of changes around her as if they were sounds or notes. The larger the change, the more "sound" it makes and the more easily she can "hear" it at a distance, making it hard to actually hit or attack her at close range since she would be able to "read" the changes around her, like the compression of air as something moves through it or the tension in the muscles as they relax and contract.
Natural changes sound safe and calming to her, while unnatural changes sound dangerous and exciting to her.

She can't use her domain to cause change to other god's, as she can't mess with divine cords.
And in the case where she and another god are trying to mess with the same thing, she would no doubt lose every time, as her widespread functionality would pale in comparison to a god focused on a specific thing, much like magic is. Funny enough, she'd probably even lose to magic if it set off a spell that would manipulate what she's messing with.

Very much childish, but also very much mature. 
As childish as she is mature, as mad as she is sane, and as intangible as she is physical, the goddess of change is known not for her stability, but for her consistency in fluctuating as she pleases, with her personality dependant upon her mood and her form, while her morals are all but non-existent. Many say this is quite reflective of her domain, but it's actually the result of her rather awkward growth from a divine cord into fully fledged goddess, for she was originally to have no set form at all, constantly shifting between the myriad possibilities present within the world.
But from the moment of her inception, she was affected by her very own nature, and instead took the form of a human child, full of curiosity and confusion. For though she could sense the "sounds" of her domain around her, she could not replicate them, much like a child handed an instrument being told to learn and play by ear. Wondering why she couldn't replicate such natural changes, she decided to take to the world and travel.
[/hider]