Hi all,
I'm very new to P6, so I'm sorry if my question is a stupid one or be duplicated.
When I change the duration parameter as the following figure (80% in this case):

The trouble is raising with Labor Units:
Their budget was set as 640
With the change of duration, my expectation is the remaining should be: 640 - 512 = 128 instead of 320 as you see.
How can I overcome this trouble?
Thanks for your support.