Currently I select a column and then chose "Text to Columns" then "Finish"
and the green triangle will vanish from cells within this column. I know
there is a way to copy a cell with the correct format and paste this format
to all selected cells using paste special but when I do this, the cell
contents are replaced by the contents of the copied cell.

Again, I know there is a simple way to get rid of the green triangles.
Someone showed me how to do this one time but I no longer am able to do this.