The inputs and outputs of functions and function blocks are referred to as formal parameters.
For basic and firmware library blocks, the properties of a formal parameter can be displayed using the 'Formal Parameter' dialog. To call this dialog either double-click on a formal parameter (inside the FU/FB block symbol) or right-click the formal parameter and select 'Object Properties...' from the context menu.
In case of AND/AND_S and OR/OR_S functions, you can duplicate inputs and delete previously duplicated inputs.