When you change your master password on one device, it get changed for local database and the cloud account with which sync is ON. It doesn’t get reflected on rest of the devices (synced with the same cloud), because they are not aware of new password.
So during next sync operation, the device will download the database from cloud (which is encrypted with new password) but could not be able to open it and will throw error with message: Error syncing with cloud. Reason: Password mismatch.
Now you would be prompted to enter the master password of Enpass data on cloud. And right after entering the password, the downloaded database would get opened, and the sync operation will resume. But still in this case, the master-password of your local device has not been changed. So, if you want to keep the same master-password for all the other devices too, you've to manually change them.