If you want to prevent users from updating previously recorded actual values or allow them to modify only a few recently recorded values, use the Lock Past Actuals setting in the System Settings tab. This setting allows you to specify the number of past actual entries that the users can edit. The Benefits Plan tab, as well as the Ledger, will be controlled by this setting.

To lock past actuals:

1. From the upper-right corner, click on your user name or avatar and then select Administration from the list of options.
2. Select the Site Settings tab and scroll down to view the Lock Past Actuals setting.
3. Type in the number of past actual entries that the users can modify. 
   The users will now be able to modify only the specified number of entries immediately before the current period. All future periods following the current period will always be editable. For example,  if the ledger or benefit resolution is Monthly, a setting of 12 periods will allow the last 12 months to be edited.  
   
   If you have set the number of past actuals that can be modified, but still able to modify all actual values, it might be because you have the admin privileges. This setting will not be applicable to an administrator user. By design, an administrator will have the ability to modify all actual values even when this setting is configured.