How do I force a row to replace all the column header names?

[blais]

I have opened a table that contains multiple headers. I'm selection a subset of rows whose header doesn't match the top header. Is there a way to select a row and make that the names of all the columns, i.e. replace the header? g^ doesn't work
Or equivalently, is there a way to reset the header / column names entirely?

[blais]

Oh never mind... gz^ works.

[alecstein]

g^ also worked for me.