I'm upgrading from a 120gb PNY SSD to a 500gb Samsung 850 SSD. 

I cloned the 120gb SSD using EaseUS Todo Backup onto the larger SSD. But it seemed to copy the setup of my smaller drive. So on my larger SSD, I have 354gb that is unallocated. 

How can I merge the primary partition and the unallocated?
![disk properties view][1]
![Disk Management view][2]


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**Update**

When trying to extend the volume via disk management, I get the following message:
![disk management extend volume][3]


  [1]: https://i.sstatic.net/riDJe.jpg
  [2]: https://i.sstatic.net/uNcYb.jpg
  [3]: https://i.sstatic.net/XThPC.jpg