The thread feature in SWX is not bad, but is really intended only for visual purposes. If you need accurate threads then you will have to model them. It is not difficult to do and you should do this yourself, especially since you want to have control to make changes. The helical path is easy enough to define. If you want to use a standard thread then I suggest you get the details for the male and female thread profiles from an authoritative source such as the Machinery's Handbook.
Be aware that 3D printing threads is nothing like producing the threads with an actual tap or die or lathe. Depending on the purpose of the threads many folks use threaded inserts or just print a pilot hole slightly smaller than the actual pilot hole and then tap the printed part. Male threads are a bit more difficult. The 3D printing usually has the effect of a swelling on the threads so even though your model might have the exact thread profiles and clearances you will have on the final production part, the 3D printing likely will need to be cleaned up.
If you search this forum for threads and 3D printing of threads you will see verification of what I just told you. You might also glean some insights as to what techniques are best suited to your situation.