Assigning editing permissions for different users across different columns

Hi All,

I am putting together a corporate document which requires many different peoples access. It also requires these people to update/comment within specific columns to them.

I am really struggling with editing the columns to ensure only these specific people can access them.

Essentially I want to the document to be accessed by everyone, but column A can only be edited by Person A, column B can only be edited by Person B etc.

I've used 'Allow Users to Edit Ranges' and added a new range with a specified person - but this has not cured the problem, other people can still edit the column I'm trying to prevent them to.

Is it a case of just 'allowing' the specific person, or do I also need to 'deny' absolutely every other person to ensure that it works?

Thanks for advance!

Regards,
Simon