Hello Lesa Boettcher,
Thanks for your questions. You can easily use the acme fix images plugin for single image too.
1. Go to Media > Library
2. Select the image you want to crop
3. In the Right Bottom section you will get the options for Acme Fix Images
4. Click there to fix that image only.
Hope this above steps will help you to fix the selected image.
Regards,
Acme Supports