Somebody made the same question 3 years ago in Stackoverflow as you can see here My answer for you is the same. Unfortunately, restoring from a backup in Azure SQL Database always creates a new database. The secret here is to rename the newly restored database with the name of the original database. You will even see that the restored database once renamed it then shows all the security recommendations, automatic tuning recommendations of the original database.
So, delete existing database, restore the database, and rename it as the original database and all the backup history will be preserved.