Enable costing for person on assignment level

Summary:

Hi Everyone,

We're facing issue in enabling cost center at assignment level, as you can see in the screenshot these options are greyed out

and we would like to enable those.
I checked many support docs and oracle docs
https://docs.oracle.com/en/cloud/saas/human-resources/25a/faipc/payroll-setup-for-costing-accounts.html#Charge-Costs-to-a-Single-Priority-Account
https://docs.oracle.com/en/cloud/saas/human-resources/25a/faipc/set-up-person-level-costing.html#Allocate-Costs-to-Single-or-Multiple-Accounts
Doc ID 2477670.1, Doc ID 2540480.1
but I did no understand as I've not worked in payroll so it would be very helpful if you share navigation as well.
Thank you.

Regards,
Hrushikesh Pentewad.

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