Your production line can only produce one type of goods at a time. You can unlock additional goods and switch the production to the new resource. 

If the resource is switched, the production line needs some time to adjust to the new process 

1. To speed up the retooling time navigate to the building overview of a production Building, then click on the "adjust"-button:

2. Click on the "upgrade" button for the retooling speed and wait for the upgrade to be finished.

The retooling speed can be increased two times by 50% up to a total of 200% retooling speed.