We have a feature request filed to change the default placemark text as well.
Please update to Avenza Maps 3.7 from the Google Play Store and see if you are still experiencing the redrawing of placemarks whenever a new one is added. If you continue experiencing it on your Motorola, please contact us at help.avenzamaps.com by tapping “Get Help” to the right side of the page. Please let us know if you experience the same thing on your iPhone 7 and we can do some testing on our end.
All the best,
Avenza Systems Inc.