Black out window shade torsioning?

[kingsboy48]

Hi, I have a couple of blackout shades on interior windows that do not roll up as quickly/tightly as I think they should. I removed one from it's valance but which end of the shade should be tightened and in which direction? Each end of the shade has the same hexagonal hole and I've not noticed anything on the ends to suggest which end is which but I maybe mistaken (there has to be a first time eh!).
Thanks in advance.