What you're finding is they have a mind of their own and varied preferences, not that they're moody.
I try to get her to step up
I'd suggest a mind shift from that to, "when I ask her to step up...".
Currently, if she doesn't want to step up when you ask, what is your response?
- If you press the matter and use force you're telling her their choice doesn't matter (damaging your relationship over time).
- If you respect their choice, you're showing that you understand the communication she's giving (solidifying your relationship over time).
Unless the house is on fire and compliance is required, it's best to think about it as asking if they want to step up, and respecting what they want.
Now you're probably thinking, "but I need to go to work", or some such thing that's very important to you and entirely unimportant to her.
If you want to avoid non-compliance in certain situations you'll learn how to proactively avoid them, not reactively deal with them.
Proactive options and allowing voluntary choice beats reactive use of force every time.
How much have you read about positive reinforcement, antecedents, consequences, etc in animal behaviour conditioning?