Cannot copy large files to USB that still has free space

ex: Situation:
I have a game installer about 5gig of file size.
My flash drive has 8gig of free space and newly formatted.

Problem:
I cannot copy large files such as ISO files in to my usb/flash/pen drive/disk even if my usb drive still has large free space available. It keeps saying "DISK MEMORY FULL".

1st Possible Solution:
**WARNING** this will erase all of your files in your usb drive. Format your computer by doing right click on your drive then choose format. A new box will pop-up check quick format on format options. Wait for it to finish.

Explanation: Maybe your USB has viruses inside it that is eating up the memory space.

2nd Possible Solution:
Formatting your USB this way. This kind of formatting will not erase any files inside your USB.
On windows RUN command type "CONVERT X: /FS:NTFS" where X is the drive letter of your USB. A box will Pop-up with writing on it wait for it to finish or close it self.
You can now copy large files on your USB drive.

Explanation:
2 kinds of format on drive:
1. FAT32
2. NTFS
Most USB are FAT32 on default format. FAT32 has a limit of 4gig file size. That's why you will format your USB using this "CONVERT X: /FS:NTFS" to convert it to NTFS which can handle very large files.