I have bifold doors on my foyer closet that were removed to install new flooring. They did rehang them but now the doors do not stay closed completely. Seems to me to be something with the spring at the top????
if they worked ok before then try adjusting the top pivot in either direction to bring the door closer or away from the spring when it shuts.you may need to play with the bottom pivot also if it was taken off when the floor was done.