How long ago did you start back up with these exercises? I know I've felt the same way with some exercises in the first few weeks I start a workout. Basically your nervous system doesn't know how to recruit your muscles correctly when you haven't worked them out for a long time, so it just kinda uses whatever muscles it likes to use best (in your case, your arms). It's a pain too because you'll do an exercise and it'll be hard to do, but you won't feel like you got a good workout.
Eventually, though, your nervous system learns better motor recruitment, and it will start using the correct muscles and you'll be able to feel like you're doing the exercise correctly. Just make sure you stick to the proper movement during the exercises and after a few weeks your body will figure out what it needs to be doing.
If you've already been doing those exercises for the past month or more, then I'm probably off the mark and maybe you just need to try some other exercises. Decline bench press
targets your sternal portion better, I think... also I really like the close-grip pulldown
for targetting the lats, although I should probably do the wide-grip to target a larger variety of muscle fibers.
Hope that helps.