Before you spend any time banging your head against the wall on this, please note that SQL Data Tools schema comparisons do not work against SQL Azure Basic databases. It will fail with some kind of timeout error. Do not be tempted to start messing with your default SQL timeouts. The default is already 60 seconds and thats plenty of time for almost everything you will encounter.
To change your edition (and there are many reasons to, not least point in time continuous backups and geo replication), you will need to go to the Scale tab on your database and select at least a Standard subscription type.