You need to test your over head flexibility before atempting overhead presses. Most of the time we are sitting and this can cause our shoulders to slouch internally. THe back is overly rounded at the top and will result in lack of overhead mobility.
You can check your over head mobility with this easy test all you need to do is follow the instructions and have a person watch your movement.
This article was sourced from Men's Health and the following images belong to Men's Health.
Stand tall. Take a deep breath, and then exhale. As you breathe out, lift your arms straight overhead as far as you can.
Fail: In order to bring your arms overhead, you must excessively arch your lower back (a.k.a. go into lumbar extension).
Fail: In order to bring your arms overhead, you must move and tilt your head forward
Pass: Your arms get overhead with zero compensations. Congrats! Go press things
Failed? Then overhead pressing isn’t a great fit for you—at least right now. Sure, you could try it, but sooner or later, you’ll get hurt.
Instead, try the single-arm landmine press.