I assume one of two things is likely the case:
1. There is a little lock icon listed next to that setting
or
2. All of those options on that tab greyed out
In the case of #1, your CATIA Administrator has that option disabled intentionally to prevent that option from being used at all. If this is the case you will likely need to request that be changed by the Administrator.
In the case of #2, the option 'Prevent Generative View Style Usage' is disabled in the Mechanical Design > Drafting > Administration tab. If this is the case and that option is available to be modified, you can Enable this option and that will free you up to modify those settings in the Mechanical Design > Drafting > View tab. Keep in mind, those options will then become the defaults for every drawing view you create after than modification and you will no longer be able to utilize any of the Generative View styles that have been defined in your CATIA Environment.
--Doug