How does locking system work on Fuhr lock with fixed outside handle?

We have recently moved into a house that has a UPVC door with Fuhr 4 bolts lock. When we first moved in the key needed to be turned 3 times to lock and open from outside, but on the inside could push handle down an close without the key. We had workmen in during the weekend and they kept banging the door shut When I showed them how to close the door I found I can only now close it with a key from the inside and it only needs a one and a half turns to lock on the outside. I think while they were trying to work out the lock it has been turned into different setting and we have no idea how to get original settings back. Can anyone advise on this type of locking system?