Alcatel Unleashed

Please guide me how to change primary port in the switches.
The switches are configured in virtual chassis.
Port 1/1/54 and Port 2/1/54 are configured as LINKAGG.
So i want to change 1/1/54 as a primary port instead of 2/1/54.

No such thing, the primary port is selected automatically. You can lock 1/1/54 to have it switch over to 2/1/54.

Why does it matter to you which port is designated as primary?

the first attached port of a LACP will be the primary. So if you disable the actual primary for a short time than the other one will become the primary.