Once an Authentication System has been added to the configuration, the settings related to SSL are non-editable fields in Desktop Client. However, these can be updated through the use of the setdbparms command utility that exists on the DE manager server(s). If you are taking advantage of HA functionality in your environment, then you will need to make this change on both the primary and the standby servers.
For example: ./bin/setdbparm javax.net.ssl.trustStorePassword
Reference: Configuring the Database Connection