Peter was referencing the '
Show Individual Frames' option in the Media Page's Media Storage panel ... turning that option
off automatically presents sequentially numbered image files as a single stitched clip that you can thereafter import to your Media Pool and use as a regular clip. For individual frames that you have already imported, and that you specifically want to continue to manage as such, changing the standard still duration to 1 frame in your user preferences, per Uli's instruction, is the way to go.
Let's have a return to the glory days, when press releases for new versions included text like "...with over 300 new features and improvements that professional editors and colorists have asked for."