change anonymous access settings options disabled

Prob Definition:
Inorder to explain the prob definition, I will walk you through the entire Anonymous access settings froms the scratch.

While setting the Anonymous access to a document library,

1. You set Anonymous access on the desired IIS website:
   IIS -> Websites -> double click on the desired Website -> Properties -> Directory Security -> check the anonymous access box
   
2. You set the anonymous access on the web application level
   SCA -> Application management -> Application Security ->Authentication Providers -> Default -> Check the Anonymous access check box
   
3. You set the Anonymous access on the site that you desire
   Site Actions -> Site Settings -> Advanced Permisions -> settings -> Anonymous access
   
4. Now when you try to set the Anonymous access on a particular document library/list, you try to go to the document library, -> Settings -> Document library settings -> permissions for this document library -> Settings -> Anonymous access
   You get to see the available option disabled or grayed out.

Reason:

Document library you are trying to set the anonymous access is configured to allow only read access on the doc lib.

Fix:

Trick is with the Advanced settings.

Document library -> Settings -> Doc lib settings -> Adv settings -> Item-level Permissions -> Read Access -> All responses.

Note: Edit Access can be set any thing.
Show results can be set any thing