This blog is part of my series Making Data Tell a Story With SSRS Properties.
The purpose of this property is to keep column headers visible as you scroll down a page to view data.
To access the property, select the tablix and select FixedColumnHeaders.
The options are True or False.
Example: I have a matrix that display order counts and totals by year, grouped by sales region. The Year header appears when I am at the top of the rendered report.
I go to the tablix properties and set FixedColumnHeaders to True (and the Background Color to white). When I view the report again, and scroll down, I see the header at the top at all times.