@Airborne47
hello love,
that is a great question and I'm happy you came to me for help! I, too, have found myself jumping around from idea to idea--it's only natural, after all. So yes, while it can be confusing, I want you to understand that it's completely normal and even serves as a good sign because it means your imagination is running wild--and the key to a wonderful book is an untamable imagination.
With that being said, I would give yourself an ample amount to time to let yourself really think out all the possible ways your novel could go. That doesn't mean you need to have every detail planned out, but maybe an outline of the major events as a structural backbone could go a long way. My advice would be to give yourself a week, and in that week, jot down literally any idea that comes to you on a separate document. At the end, take a look at what you've written, identify what you want the purpose of your current book to be about, and try and pick out the similar themes from those ideas.
Something that I've struggled with myself is letting go of an idea because I used to think that it meant never using it again. But that's actually not the case--the ideas that deviate from the purpose of the story you want to tell aren't ideas that can never be brought to life later. They're just not the right ones for your current book! I hope this helps, good luck <3