Hi, Deborah,
You can't fully protect any image on the Internet, but you can make them less interesting to illicit art-pickers by keeping them small. When loading to social media, I resize my images to 500 pixels on the longest side (some people make them even smaller). That way, someone might lift your image, but there's very little they can do with it.
That's one reason I don't use any of the 'automatic update' features; so I can control the size and look of posted images.
Of course, resize a duplicate of your image, while the original image is stored in a safe place! :-)