This video provides multiple ways to deal with the problem of extending volumes that are greyed out. Follow the corresponding steps according to your situation to resolve the Extend Volume greyed-out issue and extend the target volume with EaseUS Partition Master.
00:00 - Intro
01:00 - Case 1 - No Unallocated Space
01:49 - Case 2 - No Adjacent Unallocated Space
03:02 - Case 3 - File System Limitation
03:43 - Case 4 - Extend Primary, But Unallocated Space is in Extended Partition
04:29 - Case 5 - 2TB Partition in MBR Disk