Switch on radio volume?

Astra Life 1.8, How do I get the radio CD30 to maintain the same volume after turning off either by ignition or pressing knob on radio. It is set to highest setting 12 on the turn on volume on the radio but I'm a bit hard of hearing and can barely hear it when driving off, this requires the volume cranking up every time.
If any one has a solution it would be grately appreciated.