The ornamental design for a seat back deviceholding apparatus, as shown.
FIG. 1 is a perspective view of a seat back device holding apparatus showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a back view thereof
FIG. 4 is a side view thereof;
FIG. 5 is a top view thereof;
FIG. 6 is a bottom view thereof;
FIG. 7 is another perspective view thereof; and,
FIG. 8 is another side view thereof.
The broken lines illustrate portions of the seat back device holding apparatus or environmental structure that do not form a part of the claimed design.