This isn't software, but is computer-related:

We just started using Canva for our publicity materials at church - non-profits can get the full version for free but even the free version has a lot of options.  I'm thinking of using it in Sunday school for the kids to create Facebook or Instagram posts about what they are learning, which are a couple of their options.  You can choose from a variety of templates or start with a blank one and add a wealth of different items plus import your own photos, etc.  One of the challenges is it can be quite a time sink, so the idea is still very much a work in progress, but it is a great resource for publicity materials for Sunday school (or other church events) as well.  www.canva.com is the website.