Updating your maps is a two stage process. First you have to connect to Anquet Cloud and bring down the latest map definitions for your account.
Then you have to select the maps you wish to update.
You do not have to update all your maps at once, only the ones you are interested in.
Also bear in mind that you will not receive ALL the updates, only those that apply to the sections you have actually downloaded to your device. So if you had downloaded the SD and NY sections of 25K mapping and you selected all 25K mapping for updates only the SD and NY would sections would be changed, not the entire country.
Originally the process was virtually the same on all platforms but over time variations have crept in so please select the appropriate instructions from the list below.