Diaper change nightmare

so my daughter is 15 months. The first 6 months of her life she hated having a wet/soiled diaper. Of course we would change her and she would lay there. No crying. Nothing. Now for the last 9 months it's a nightmare. She'll cry when her diaper is ready to be changed. We'll lay her down to change her diaper and she'll throw a tantrum. Omg it's horrible and definitely tests your patience. We've been working with her on going potty in her potty chair. Any tips on this diaper changing? Or why she does this?