Attaching New Vinyl Material to Bucket Seat Back

Your gonna need to clean the non working/drying adhesive off your parts with naphtha or acetone. It is probably easier to get new vinyl pieces but the abs plastic should clean up easily.
You need to be using landau top adhesive or weldwood contact cement.
It will come in a quart can and can be brushed or sprayed if you have an old paint gun.
Adhesives that are engineered to come out of a aerosol can should be avoided.
They never dry and release on the first warm day. The working properties of the glue are sacrificed so it can be sold in convienent aerosol form. Good for 3M selling adhesive bad for your project when it fails to hold. And it will fail since it never ever dries.