Thanks for your message. Finding the right community issue is certainly a challenge if you're not already entrenched in something going on in your neighborhood. One of the easiest ways to get involved in an issue of importance is to start going to meetings: city council meetings, community group meetings, school/PTO meetings, and even sometimes faith-based meetings have issues on their agendas that need energetic people like you to get involved and carry the ideas for solutions up to local and state governments. Finding organizations that match your interests might be as simple as visiting https://www.volunteermatch.org/, but for policy-specific issues, it will likely take some digging on your part.
If finding meetings you can attend doesn't help get you focused, then you may need to do some basic needs assessment/resource mapping yourself to help focus your efforts. The Community Tool Box has some great resources for getting started: http://ctb.ku.edu/en/get-started. You mentioned wanting to work with youth and schools, so you might look at some of the policies in your local school district or state department of education and see if there are any issues there that deserve more investigation or refinement.
The long and the short is, finding the right work for you is going to be a you-decision based on what needs to be done where you live, work, and play. I hope you're able to find the thing that really keeps you energized and allows you to feel like you're contributing.
Hope that helps,