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Best Answer
You would be better off adjusting the striker plate instead of the door. Stand where you can see where the bolt hits the striker plate. Make a Sharpie marker line there. That shows how far off the two parts that are supposed to mate are.
Let's say that the bolt is hitting the plate 1/8" too high. Then what you will need to do is raise the plate at least that 1/8" higher. The easiest way is to take off the striker plate and look at the recess it is mounted in. Now use a chisel to enlarge that recess on the top edge so that the plate can be mounted on the door frame that much higher.
Before you screw the plate down, double check how the door bolt and late will touch after raising the plate to the top of the new recess. If it is good then drill holes through the frame where the plate's screws will go and attach the plate with screws. Changing that plate location is usually easier than filing the opening in the striker plate to let the bolt pass into it without interference. But if the difference is small that might be easier.
Let's say that the bolt is hitting the plate 1/8" too high. Then what you will need to do is raise the plate at least that 1/8" higher. The easiest way is to take off the striker plate and look at the recess it is mounted in. Now use a chisel to enlarge that recess on the top edge so that the plate can be mounted on the door frame that much higher.
Before you screw the plate down, double check how the door bolt and late will touch after raising the plate to the top of the new recess. If it is good then drill holes through the frame where the plate's screws will go and attach the plate with screws. Changing that plate location is usually easier than filing the opening in the striker plate to let the bolt pass into it without interference. But if the difference is small that might be easier.
Source:
Don't mess with the panels and their hinges. They are harder to get correct if you alter them.
Other Answers (4)
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Before you try anything complicated or start cutting things, do this:
Remove the top screw from the top hinge of the door you have to lift. Replace that screw with a 3 inch long screw, driven TIGHT into the stud behind the door frame.
Usually that's enough to bring a sagging door into alignment.Source(s):
I'm a retired locksmith- My guess is either the screws in the hinge are loose if the bolt/striker plate used to line up or if they never did the hinges are installed at different depths in their mortise (recess).
Open the door and tighten the hinge screws on both the door & jamb. Does that help?
If you need more adjustment, make some cardboard (cereal boxes work well) shims using the hinge as a pattern. If the bolt hits too low put some shims behind the lower hinge. If it hits too high, put them behind the upper hinge instead.Source(s):
Done it. 
I would look very closely at where the bolt is hitting the strike plate...usually it is only slighty off due to normal shifting of the house/door frame.
You said you have to lift the door to lock it, so I am thinking you can enlarge the opening in the strike plate slightly with a round metal file on the bottom edge of the opening.- most of the time it is as simple as tightening the screws on both sides of the hinges....BUT, depending on how old the house is and how long the door has been there, it could just be out of line with the sagging and settling of the house, which is normal
