By the MBR limit, you can have 2TB only.
If you want to increase your disk over 2TB, you must convert MBR to GPT.
In Microsoft, they will ask you to use diskpart to delete volume on your disk, and then convert to GPT.
If you do that, you'll lost all data.
Now, another solution here.
You can use gptgen to convert MBR to GPT without lost any data.
GPTGEN download link:
gptgen.exe -w \\.\physicaldriveX ←On Windows
X is your disk number.
If you don't know your disk number, you can use the command:
DISKPART> list disk
After "gptgen.exe -w \\.\physicaldriveX", you must restart your PC, and you can use DISK MANAGEMENT to increase your partation over 2TB.
But... don't forget backup your data, if accident occurred!!