How can I change the heading in peekaboo?

[NateMarrocco]

   -- Customize display format to show mark name, filename, and line number
    vim.g.markbar_mark_name_format_string = "%s %s:%d"
    vim.g.markbar_mark_name_arguments = "['name', 'fname', 'line']"
    
    -- Customize peekaboo display format (what shows when you press ' or `)
    vim.g.markbar_peekaboo_mark_name_format_string = "%s %s:%d"
    vim.g.markbar_peekaboo_mark_name_arguments = {'name', 'fname', 'line'}

My attempt to format the header, but nothing is changing. Ideally Id like to get rid of the file path and have just the file name, and line number and i suppose mark name.

Thanks