Ok, I think I understand now. You are trying to sing songs at the keyboard. To get more than just the folk songs you have to level up both singing and piano to get the other song categories. On the keyboard or piano, you only have 4 categories with both skills at level 10.
So what you need to do if you want to sing songs at one of the musical instruments is to level up both singing and the musical skill (Piano, Guitar, etc).
Hope this helps.
You're losing me I think. The karaoke machine, musical instruments and the microphone all have different song categories but they do share some. For instance, folk songs are not on the karaoke machine and disco is not on the piano or keyboard. So just because you see Jazz on the microphone does not mean that it will be present on the keyboard unless you've also leveled up the piano skill enough so the Jazz option becomes available.
You've said that you singing was level 5. But what is the sim's piano skill level? You have to have both skills leveled up to see more than Folk on the keyboard or piano.
Hope this helps.
