MobileAlerts persists the configuration data in a file called MobileAlerts.ini under the Resources folder.
If insufficient file access rights are granted to the user identity under which the MobileAlerts application runs, it will fail to persist the data.
 

Follow these steps to fix the problem:

1. Find the identity under which MobileAlerts runs (in IIS Manager, look at application pool level>>Properties>>Identity)
2. At the file system level grant Write rights to the above identity for the Resources and Logs folders