I just bought a house and there is a set of 3 light switches two of them look exactly the same and work perfectly fine, but the third on looks different and when you flip the switch on it trips the breakers for the entire living room. What could be the problem and is there an easy fix?

What do the other 2 switches control? Are they located near the front door? Hallway towards the bedrooms? Knowing what they control may help in diagnosis.

Do you have any idea what it controls, perhaps another light in the area that doesn't come on? If so, check that light. You might pull the switch out and look at it. Also note how many wires are in its box, and if any of the whites are marked with black tape.

"it trips the breakers for the entire living room" the lights or the outlets? You have a short somewhere and the switch itself is the first and easiest to check. Do you have a teser or multimeter?

Problem more likely at switch box or what it is switching. See where the wire exits the
Switch box, if it goes up, maybe a light or fan, if wire exits switchbox out of the bottom,
May go th a receptacle. Do all recepticles have power when energized?
If at a front door, maybe landscape lighting. Do you have anything that doesn't work?

I have no idea what the switch controls, it is right by the front door. One of the other switches controls the porch light and the other one is for a light just above the entry.

The only light in the living room is the one above the entrance, the switch trips the circuit breaker for everything in the living room, sockets and the light.

With the switch off, go through the living room and carefully check to see if everything is hot. Everything includes both halves of duplex outlets. By breaking off a tab, you can wire outlets for one half always hot, and the other switched. Look around outside for where there may have been a lamp post or something.

You can go back on the seller for defects too. Usually not worth while for minor stuff, but gives you some leverage to be told what the switch is for.

I just bought a house and there is a set of 3 light switches two of them look exactly the same and work perfectly fine, but the third on looks different and when you flip the switch on it trips the breakers for the entire living room. what could be the problem and is there an easy fix?
No easy fix, sorry. The short has to be located and it could be anywhere. If your house has electrical piping I would start by determining the path of the raceway all the way back to the panel and check every junction box along the way for the source of the problem, If your house has "Romex" the same applies except that it may be more difficult to map the circuit. If you're not qualified to do the work simply don't operate the switch until you can find someone who is.

You said the switch looks different, howso?

The two that work are fatter white switches and the one that doesn't work is a skinny black switch

Can you provide pictures?