Read each client's real DNS request, then build the zone yourself: add the exact records (type, name, value, and priority or TTL where it matters) that satisfy it.
Each client states a real DNS need in their own words. Click "Add Record" to build the exact records that satisfy it: pick the type, the name, the value, and (for MX) the priority or (where it matters) a specific TTL. Click a record you already added to edit it, or use the small delete control to remove it. Click "Deploy Zone Changes" to see what happens. A wrong record type, a wrong value, a missing record, a wrong MX priority, or a CNAME that conflicts with another record at the same name all have a real, specific consequence. Fix the zone and redeploy until it is right, then move to the next client.