To soften a fabric couch, start by vacuuming it thoroughly to remove any dust or debris. Next, mix a solution of equal parts water and white vinegar. Using a soft-bristled brush or sponge, gently scrub the couch with the solution, focusing on areas that feel stiff or scratchy. Allow the solution to sit for 15-20 minutes, then wipe the couch down with a clean, damp cloth to remove any residue. Finally, fluff the cushions and pillows to help break up any remaining stiffness. Alternatively, you could also use a fabric softener to soften your couch.