The ornamental design for the convertible adjustable zippered screen apparatus, as shown and described.
FIG. 1 is a front elevational view of my design, shown with the screen in a partially unzipped position;
FIG. 2 is a top left perspective view of my design;
FIG. 3 is a right side elevational view of my design, the left side being a mirror image thereof;
FIG. 4 is a bottom plan view of my design;
FIG. 5 is a top plan view of my design;
FIG. 6 is a front elevational view of my design;
FIG. 7 is an enlarged fragmented front elevational view of the fastening mechanism illustrated at the upper left side of FIG. 6;
FIG. 8 is an enlarged fragmented front elevational view of the fastening mechanism, illustrated at the lower left side of FIG. 6, with the fastening mechanism in operation; and,
FIG. 9 is an enlarged fragmented front elevational view of the fastening mechanism illustrated at the upper center of FIG. 6.