You can do a dirty flash but with a new OS version is recommened to do a full wipe. If you want you can do a data backup to restore it after the update
Next release will be BETA testing of Oreo update, probably with a stable release will be better. Now in DEV I have problem with bluetooth and battery drain probably with 3 hours of screen...try to wait or pass to LineageOS, your choice!
Ciao, l'ultima ROM disponibile è la 8.9.14 con MIUI10, sei rimasto un po' indietro ahah ti conviene scaricare l'aggiornamento dal telefono o dal post https://xiaomi.eu/community/threads/8-9-13.46383/ ed installarla tramite recovery o updater
To install the gloabl you have to lock the bootloader but if you bought the phone from China you can't lock the bootloader and use the Global. With the new stores in Europe, Xiaomi blocked the purchase from China and use in EU or other countries to avoid people to spend less and problem with...
Is right in this way, phone and headset have their own volume. You can set to MAX to the phone but "low" to the headeset, are not linked. I don't know if you can sync, but i don't think
It seems on new version the database was changed and there is no way to downgrade, probably the only method is wiping all and if new messages backed up on MiCloud were saved with new version...deleting them