Bert,
What do you mean 'monthly inputted forecast'? In VV, the whole purpose is to forecast based upon previous consumption. The system calculates a statistical forecast, which you can manually adjust/override.
How are you 'inputting' your forecasts? Did you actually execute the forecast run?
Carrying Out the Forecast - Forecasting (LO-PR) - SAP Library
Using M/1/2/4, your forecast will not be split into weeks. The first month will be split into days; then the second and third month will be split into weeks. The remainder of the forecast is not split.
Best Regards,
DB49