Welcome to Justanswer.com, my name is Dustin.I'm sorry to hear about the issue you are having, I will do my best to help you resolve it.
To get started, I need to know what type of computer you are using, a Windows XP, Vista, Windows 7, Windows 8, Windows 10 or a Mac.If its a Mac, please check the OSX version as follows, Click the apple sign at the top left of your screen, then click about this mac. And then where it says version, send that to me as a reply.
Also, do you use a phone to access your gmail account, if so i need to know the name brand and model of the phone, thank you.
The quickest and most efficient way in which I can help you figure out exactly whats happening, is through a screen sharing session. That way I can help you directly on screen.
Since this issue is very straightforward, I will reduce the cost substantially and send that offer to you now.
If you would prefer written support alone, do not accept the offer and reply " Written support please"
I did look at your specific question, and I specifically responded to it.
I understand the ins and outs of googles device tracking, security measures, apis, account security, device history, etc.
On one hand we could just change your password ***** security info on google, and could call it a day.
But, what we dont know until we DIG into your google account settings is if at some point your account was actually accessed.. If it was, that account can be used to spread files and programs to your devices, and if you have google set to save passwords, all yoru passwords could be at risk. I am not an alarmist, this could be a simple error.
I offered you a screen share at a reduced cost because this will make it easier and less time consuming for both of us.
If you prefer written support, thats fine too.
Just let me know how you want to get started.
Lets try this.. Use a browser, sign into your gmail account in that browser. Then, click this link first
Are all devices in your normal city?
If they are.. Then simply run through all the steps on this security checkup, https://security.google.com/settings/security/secureaccount?continue=https%3A%2F%2Fmyaccount.google.com%2F
And call it a day..
However, if on the first link you see devices that are from outside your city, or outside your immediate area... Then we need to consider some stronger security actions.. So please dont consider this a full answer.. Whether or not we go through more will depend on that first link, and what it shows.. So keep me posted!
You cannot change the username.. What you can do is delete the gmail account, without deleting the google account ( for google drive, registered phones, google photos, youtube history, calendar, etc )
Deleting your gmail and then adding a new gmail account to your google account would defeat the login attempts..
With that being said, Some possible causes of this could be, if you have an email client such as Mac Mail, Thunderbird, OUtlook 2013, windows live mail, or windows mail.. And if those clients are running and have your gmail attached to them but have the incorrect or old password, they could be trying to periodically sign in to check your mail, and failing//
Of course, there isnt a way to rule out that someone else is trying to guess your password..
What model of Samsung phone is it that you have specifically?
And my apologies for the delay in getting back to you.. Today was a very long, unwanted day off.
Most likely on your phone, all we would need to do is go t o you settings, accounts , and then remove your google / gmail account.
And then once removed, restart the phone and then add the account again.
Ok, to be clear.. you do not want to be inside of googles actual settings, dont delete anything there.
Instead, on the phone itself, go to the h ome screen ( the phones home screen )
Go to settings ( in the phone ) then accounts, and delete google from the phone.