How do i start new story lines?

Yes but where and how do I start another story on the Sims

I need help with that too, I accidentally pressed “choose later” and now I don’t know what to do.

Maybe you are tapping on "Choose Later"? If that is the case, when clicking on the puzzle piece or the suitcase, after the dialogue window appears, tap on the icon of the job/hobby you want to select. Jobs require to unlock the the job place

can you give us a photo so we can help you?