What's your code for each button?
When you say scene, what do you mean? symbols? or are you using Animate CC and not Edge Animate in which case you need to go to the Animate CC forum and ask your question there.
If you have button symbols on the stage for next and previous, each of those symbols has an instance name with an event listener attached to it. The event listener is connected to a function. You can only have one event point to one function. So, if for instance, you have a next button and a click event that points to a function that says something like nextFrame();, and then you want to use the next button to point to a function that says something like nextScene();, you'll have to use a different instance of that next button, and have that different instance use a different event handler to point to a different function. Does that help?