Your Preferred Territory is the default territory that your artist, track and playlist data will use. Spotify Add/Drop reports, Spotify Playlist Adds alerts and Spotify Charts Peak alerts will send you alerts specific to this territory, in addition to global alerts.
Your Preferred Platform is the default platform that your artist and track data will default to.
To change your preferred territory and preferred platform, click the artist icon at the top right and choose Profile & Alerts. From there you can change your preferences: