How to refactor the visibility of an abstract member?

It seems no one has such problem,

help...

Reshaper can't do this for you. The moment you alter the accessibility of a method that is used OUTSIDE the class, you would create an error.
To protect user from themselfs, Resharper refused to alter code that doesn't compile.

If the method is only used inside your class, that just change one method, you the copy (ctrl-C) the 'protected' keyword and paste it over the the public statements of the remaining overloaded methods.
To be safe, recompile the solution and check for compile errors. If none found, refactory completed..

Hope this helps,
Dave

Thank you for your information, :)