Measure the length of one of the sofa cushions to determine how long the fabric fastener strips need to be. Cut four fabric fastener strips to fit the measurement. The strips should be two matching sets; two hook strips and two loop strips.
Sew one fabric fastener strap vertically to the center of the underside of each cushion, using a standard needle and thread. Sew the other fabric fastener straps to the couch, matching the position of the straps on the bottom of the cushions.
Place the cushions on the couch, securing the hook straps to the loop straps to adhere the fabric fastener closures into place. The fabric fastener straps should keep the sofa cushions from slipping.