1) Go to Common Module > System Security > System User Group > select particular DynaMod user group which going to configure the cost column display option (kindly take note this will effect all user under same user group, suggest go to Common Module > System Security > Setup System User to verify before proceed next step configuration), click More button then select Access Right Maintenance.
2) At pop up User Group Accessible Object Maintenance windows, go to Inventory Module ID > Setup > Stock > drag down into bottom to choose to enable / disable the cost display option
P/S : Reference Cost was non system calculated cost, can be update by manually, normally used by business owner to enable this for their Sales Team for reference cost without display the SKU actual cost.
Sample Stock Maintenance screen when only Reference Cost was set to display hide the system cost.