If you have experienced your switch loosing its settings on a power down or power cut you are not saving the existing configuration to the boot config of the switch.
The switch has a feature that will allow you to make changes and temporarily save them until a power reboot or to commit the changes to the switch boot config. This feature is great if you make a configuration mistake (as long as the settings haven't been committed). You can simply reboot the switch and all uncommitted changes will be discarded.
In order to retain configuration changes after a switch reboot or loss of power, simply click the 'Disk' icon in the top right hand side of the switches web browser screen.
Once the 'Disk' icon has been clicked you will get a confirmation message asking if you want to save the current running configuration to the Startup-config. This will retain all settings on a power cycle.