The first time 4.x starts on a device that had classic DMD2, it asks you. The dialog is titled Welcome to the new DMD2 and offers two choices:

• Migrate my data — keeps your settings, GPX files, saved locations, roadbooks, licence and sign-in.
• Start Clean — sets up fresh and frees the space the old data was using.

Your downloaded maps are kept either way. They are picked up where they already are, so there is no re-download and nothing to move.

Nothing is read or changed until you answer. If the dialog is dismissed, it comes back on the next launch.

What Migrate brings across: your units (mph, Fahrenheit, psi, 24-hour clock), app language, map storage location, your odometer and trip totals for each profile, your licence key, and your HUB sign-in so you do not have to log in again. GPX files from the old Imported and Recordings folders come over, along with your saved locations and imported roadbooks.

What it does not bring: map theme, warning settings, dashboard layout and device pairings. 4.x is a different app underneath, so those start at the new defaults. Set them up before your next ride rather than at the roadside.

After migrating you may be asked Update your maps?. Your existing maps are ready to use and you can ride right now — downloading them again in the new format is what adds offline address search and speed cameras. Tap Later if you are not on Wi-Fi; it is always available again from Map Downloads.

If your HUB account already holds settings and trip data from another device, you are asked which set wins: Keep this device's data or Use my HUB account's data.

Two cautions:

• If you keep your maps on a removable SD card, choose Migrate rather than Start Clean. It is the safer path for that setup.
• If your old GPX files and roadbooks lived on an SD card and you are on Android 11 or newer, check they actually arrived. Newer Android versions restrict what an app may read from a card, so you may need to import those files by hand.