I uploaded some data in CSV and it made no effect - why didn't the data update?

After uploading data you need to press "Recalculate" on the order plan for it to take effect, and for all your forecasts and order quantities to be recalculated. 

This will happen automatically after the Sales Orders upload. But all other uploads need to have the Recalculate kicked off manually so you have a chance to upload all your data before the system starts recalculating the forecasts (which can take a few minutes).