Hi Eric – this kind of challenge usually (but not always) comes down to your concept and your value proposition. Why is it that people would want to engage? What challenge is the community going to solve for them?
The fact that most people that sign up don’t return implies that they are not seeing anything of immediate value. This could be because assumptions were made about what people wanted or needed when the community was conceptualised.
You mention that you know they have questions about your products – how do you know that and are there other places that they might be getting that information?
This article is an interesting read:
The fastest way to diagnose the problem is to actually ask people. What challenges do they have that your community could solve? What is it that has stopped them from returning?
In some cases it could be a platform issue. Is it easy to sign up? Is it easy to find the community and ask a question? Is your website designed to drive that behaviour?
More info here:
What does your onboarding journey look like? Are people reminded about the community after signing up? Is the barrier to making the first post low enough?
Other related reading:
I’ve thrown in some pretty generic resources here because every community is unique, but those might give you a starting point for diagnosing the issue.