Password Problems with Gmail?

Ok So I have 3 email accounts with Gmail, I'm having the same issue with all of them.

I sign in to my Gmail using google chrome on my laptop, it tells me my password is incorrect. So I reset it.
Then when I go to use my Gmail App on my iPhone, it tells me this new reset password is incorrect. I try my old password, still incorrect.
I have since figured out that I have to change my password to the same thing on both devices for it to work.
But recently, I had to change my password AGAIN because I had to sign in on my email on my Bosses iPad, new device so I had to change my password on that, then on my own iPhone, then on my laptop. When I sign in to one device, it signs me out of all other locations and then when I try to log back in, it tells me my password is incorrect again.
I'm running out of passwords here! And patience! (It doesn't help that the new passwords have to contain uppercase and lowercase and numbers and punctuation and hieroglyph and the blood of your first born child!)
Someone Please help, I'm ready to boycott emails at this point!

Get a new account or email GMAIL themselves.

There are two ways you should try:
when you are typing your username and password, you should pay attention to your selected language on your laptop, uppercase and lowercase to type EXACTLY the password you typed before.
second thing is, you should check with Gmail that you can log in with different devices at the same time or not! Maybe Gmail logs you out from your account automatically.