Save as in original folder

How do you "save as" in the same folder as the original document. When I open any file on my hard drive, and make some changes, but want to keep the original, when I try to "save as" a different name, the original folder where original document came from, is not the default, or even a choice on the "save as" screen

There should be a small disclosure triangle next to where you input the document file name.

If you click on it, it will expand the Save As box and allow you to select a different folder to save the document to.

If you are talking about programs like: Numbers, Pages, Keynote... directly under the save button in the File menu there is a button for duplicate.