My Book 8TB problems

Got a brand new 8TB my book yesterday and I am only able to access 2TB of storage. When I try to extend or resize the partition I am told the drive is MBR and nothing over 2TB can be accessed. How do I access all 8TB as I should?
Thanks

Go to Knowledge Base tab and search on ID 1088. You should be able to select GPT option. Or partition the drive for other sizes (2tb is a lot of space).I have a 1TB drive with 4 partitions and much data, but not a lot of videos.

I hope this helps.

Thank You