Edit Web Item in WAD 3x

Hello Experts,

Problem Statement: We have Web Templates where there are certain web items for which we are unable to change the properties! Below is a header bar web item which is appearing in the Standard Web Items section but it has been configured to refer to a custom ABAP Class instead of standard i.e. Y_CL_RSR_WWW_XXX_HEADER. Now part of a new requirement we are to refer this web item to a new ABAP Class, how do I do it?

Can you please help

Thanks

Abhishek Shanbhogue