I mean if they seem stubborn toward something due to prejudices & we have things to tell them that could turn around their judgement on certain things & for the benefit of the relationship.
I enjoy hearing other peoples ideas & opinions so I cant see why its such a hard task to get an aquarius to listen to you. I am generally understanding too but that doesn't mean you are going to change my views.
Just do it diplomatically, don't force it on her, or don't be arrogant about it. Talk it out gently and listen as well. The more humble you are, the better you will be, and just because someone has a different opinion by you, it does not make that person a bad person. P.s. It's not about signs. It's about fellow humans.
Maybe they're genuinely NOT INTERESTED in what you have to say!! I agree with Kiwi - I'm an Aqua and I enjoy listening to other people's ideas and opinions. My boyfriend is also Aquarius and he's quite open to listening to me and taking my suggestions on board