The grubscrews are for tensioning the blinds, the flyscreen and blackout respectively.
They need to be pushed in, and held in, with a flat bladed screwdriver and tightened, clockwise then let back out to engage with the locking mechanism.
If you let the screwdriver slip the spring will release all the tension and you start again !!!!!
The ideal tension is that when required, the blind retracts at a reasonable speed, but NOT fast enough to come to a jarring halt.