Bifold doors contain two separate door panels that are connected with hinges, forming one bifold door. Depending on the size of the door opening, it holds either one or two sets of bifold doors. Whether your bifold doors contain two panels or four panels, adjust the doors similarly if they continually pop back open after you close them. Tools are necessary only if you need to adjust the bottom or top brackets, which you may not even need to do.
Slide the bifold door open. Look up at the end of the door track where the door stop, called a snugger, is located. The snugger is a small plastic piece with a metal spring inside it. If the doors push against the spring too strongly, the doors pop back open.
Slide the snugger spring further in, towards the side door casing. The casing is the trim around the perimeter of the door frame. Adjust the spring so that it is centered within the snugger, if you have four bifold door panels.
Slide the snugger within the track, so that it is centered evenly between the four bifold door panels. Slide the snugger closer towards the side casing if you have two bifold door panels.
Close the bifold doors and see if they pop open. If they do, lift up on the bifold door and slide the bottom of the panel that is nearest the door casing to the side, so that the bottom pin slips out of the bottom bracket. Lower the door down from the overhead track.
Loosen the screw in the top bracket within the track. Slide the bracket towards the side door casing and tighten the screw back. Use a Phillips screwdriver. If the bottom bracket is adjustable and doesn't just have a long slot for the pin to slide into, loosen the bolt in the bracket with an adjustable wrench. Slide the bracket closer to the side casing, and tighten the bolt back.
Push the door up into the top of the door frame, so that the top pin fits into the top bracket and the roller enters the track. Lift up on the door, slide the door bottom above the bottom bracket and lower the door so that the bottom pin slips into the bottom bracket. Do this for both sets of bifold doors.
Slide the bifold doors open and shut to make sure they don't pop open after you close them. Adjust the top and bottom brackets again, if necessary.