Turn on Training classes in Settings to plan CM training here. It lists who's due (training that runs out within the months you choose, or none on record). Plan it and invite emails each of them the date, the place and your notes, with I'll be there and I can't links that work without signing in, and a calendar file. Those who say yes get reminders 7 days and 1 day before. The class shows who's coming, who can't and who hasn't answered.
When your policies change, choose Invite: Everyone: a refresher to invite every adult on your teams, not only those due. The invitation says it's a refresher on what's changed. A new version of a policy to sign already asks everyone to sign it again.
After the class, tick who came and press They came: record … training dates in Planning Center. Each person's "CM Training Date" is written into Planning Center as you (you need to be able to edit that field in People); anyone Planning Center refuses is listed, and you can finish them in Planning Center. Arkrooms keeps the class and the answers for a month after it, and never the dates.