Factory reset before selling phone?

[anon(8404556)]

I got a Galaxy S5. I plan to sell my Galaxy S4 soon. This leaves me with 2 questions that dictate if I will sell my phone. I've taken out the SD card and also deleted all the files on phone storage in My Files app. Things like texts and photos have been deleted from the S4 and moved to the S5 so there's nothing on the S4 I want to save or back up. Since there's nothing to keep I'm going to Settings> Accounts> Back up and reset> Factory data reset to uncheck the box for 'Back up my data' and then clear the phone by pressing Factory data reset. When I uncheck that box it asks me to confirm that its going to delete "all copies from Google servers".

1: I'm worried that this will prevent me from logging into my accounts on my new S5. Is it okay to uncheck this box and let it delete?

Also, will the factory reset remove everything and return it to like the day I first bought the S4? I am worried that if an app I previously had is installed again by the new user, if the new user tries to log in to their own email with the email and gmail apps I used, or lastly, uses my previously used widgets like Google search bar and Google Now that my accounts will be remembered or even still be an option in the list of accounts to login to on the phone.

2: Will the factory reset be able to clear all the things I'm concerned about?

I would try to figure this out by trial and error but the first question prevents me from doing so, just in case it actually does affect logging in to my accounts on the new S5. I don't feel comfortable selling my S4 to a stranger until I'm absolutely sure there's no way my information can be stolen from the S4 by a new owner.

 

[beagle82]

Q1: unchecking that that box will delete your wifi passwords, app data etc from googles servers. You don't want to do that, as when you sign in with the new phone, all that data will be synchronized to the new phone, which could save you some time.

Q2: factory reset will return it to the state you purchased it. Completely new with none of your personal info. After the reset, it will bring you back to the initial sign in page where you have to enter your account and password like you would have to do with the phone straight out of the box.

 

[Rukbat]

Factory reset removed any downloaded apps and any entered personal data.

Turn on airplane mode and do a factory reset. In airplane mode, the phone can't contact the servers. Then check Settings/General/Accounts. If your Google account is still there (it shouldn't be), delete it.

Now if the phone is out of airplane mode, it has no Google account to refer to, so it can't delete anything from the servers. (Make sure that you have everything backed up the S5 and at least one cloud account anyway.)

 

[anon(8404556)]

According to the post after yours, in order to prevent the data that's been deleted by unchecking the box from synchronizing to the new phone, I should simply enter airplane mode first, uncheck the box, then do the factory reset? Then as suggested I will check Settings>General>Accounts to see if my account is still there.