TurboTax automatically uses the Short Schedule SE if you qualify for it. If you have something that requires the Long Schedule SE but you have not yet entered it, TurboTax will switch to the Long Schedule SE when you enter the item that requires it.
If you are using the CD/Download software, you can force it to use the Long Schedule SE, even if you qualify to use the Short Schedule SE. In forms mode, open the Schedule SE Adjustments Worksheet. On line A near the top of the worksheet, check the box that says "Use Long Schedule SE, even if qualified to use Short Schedule SE."
There is no way to check that box from the step-by-step interview, and therefore no way to do it in TurboTax Online.