I think the common problem here is that it is instinctual to select the ROW(s) we want to freeze, and it isn't working. The instructions say "based on current selection" so you figure "okay, I've got what I want frozen selected, why isn't it working?"
They didn't write the instructions very well, lol.
Do not select the entire row and expect it to freeze those rows. Instead, select the FIRST cell in column A of the row you do not wish to freeze, then select Freeze Panes.
Also, if you wish to freeze columns as well as rows, this same applies, but you will then need to select the cell further down the row. For example, let's say you want to freeze the first two rows AND the first two columns. You will need to select cell C3.
This will cause Columns A and B to freeze, and it will cause rows 1 and 2 to freeze. Always select the first cell you don't want frozen, contrary to the way the instructions sound, lol.