OK, Adobe's pricing and marketing strategy suck big time. And while Acrobat Pro 8.1's image placement tool worked fine under XP Pro (rev. 3), not so much under WindoBUT, there is a work around that isn't too bad (do NOT let Adobe give you an 'upgrade'...a Trojan horse). It worked for me above any other strategies and implies a kind of formatting incompatibility...one that can be finessed, however.
Adobe has a number of standard beneath its PDF umbrella, including PDF/A, PDF/X, and PDF/E, which in turn each have several sub-variants. The A is optimized for archival purposes and is what federal courts require. The X is optimized for graphical related uses and images, while the E is best for engineering uses, schematics, and blueprints.
While every image type file I had failed to be 'placed' with Acrobat Pro 9's object touchup tool under Windows 10, it became possible once I struggled with its 'preflight' option under the 'Advanced' tab. There I discovered numerous options including PDF/A, PDF/E, and PDF/X compliance. Since I wanted to insert a signature and some pics into my PDF document not intended for court archival purposes, I tried to guess conservatively with the PDF/X compliance choice.
Within that category, I opted for 'convert to PDF/X-1a (Coated FOGRA39), then clicked on the Analyze & Fix' button near the bottom of the frame. Once the app had completed the conversion, I saved it under a different filename. Finally, I successfully used the Object Touchup tool and 'placced' the image about where I wanted it in the PDF document, then resized it to my wishes and moved the image to where I wanted it. It accepted JPG image files in this instance. Upon saving the completed editing work, it remained intact upon reopening.
p.s. Adobe, thank you for a fairly decent PDF application, but F U for your arrogance, greed, pricing scheme, and attitude toward consumers. You have p*ss*d in the punch bowl so often, folks have lost their taste for it.
p.s.s. Others who find success with this work around are invited to comment on and add to it.