Default file settings
Settings » Files tab. There, you will see a page like the screenshot to the right.
This is where you go to set up the default file upload settings: what folder the files should be uploaded to, what file types are permitted and the max file sizes. Now, any new file upload fields will automatically pick up from these settings. And if you choose to change the values when your forms already have files uploaded, the settings will immediately take effect and files will then be uploaded according to the new settings. No additional configuration required.
But the File Upload module also provides some additional options, only configurable on a field-by-field basis. For that, see the next page.