Select the Preferences menu under the Cabos drop-down menu:

Click on the triangular button next to sharing. This will drop down the Sharing menu. The default setting is to share files in your Downloads folder (path / Users/x/Downloads, where x is your mac computer user name). Right click on this folder and click "Remove." Also, uncheck "Share partially downloaded files" and "Share completely downloaded files." This will further limit the uploading capabilities on Cabos. Limit both "Maximum uploads" and "Maximum uploads per person"to 1 (this is the minimum number allowed by Cabos) and limit "Upstream bandwidth limit (%)" to 25 (this is the minimum number allowed by Cabos):

Click on the triangular button next to Network. This will drop down the Network menu. Uncheck the boxes that "Allow this computer to become an Ultrapeer"and "Allow freeloaders to connect to this computer:"

Suppose that you see an upload occurring, even under the specified limited settings. To cancel the upload, click on File, then click on Main Window:

Under this main window, you can click on Uploads to view current uploads. To cancel, highlight the file being uploaded and click "Remove:"