I Keep Getting Facebook Login Notifications .....

[Gizmonster]

So every time I log into Facebook using the android app on my phone, I immediately get a notification along the lines of, "you don't usually log in from this app, so we need to check that it's you".
I follow all the prompts including the "remember this app" so it will recognise me the next time I log in ..... but the next time I log in I get the same notification.
Now, apart from disabling login notifications (which I don't want to do for security reasons) how do I stop this and get Facebook to eventually realise that i'm using the same app to log in each time??

[barry1010]

Do you use a VPN?

[Gizmonster]

//// Do you use a VPN? ////

No, not on my phone.

[rockyracoon]

Are you in incognito/private mode without realising it?

[Buenchico]

Any use?
https://m.facebook.com/help/261055370579217?locale2=en_GB

[Gizmonster]

Well that was weird .... it's sorted now.
This had been going on for a few weeks and I just looked in all my settings, etc but I couldn't find anything out of the ordinary.
Anyway, I have another FB account that I occasionally use and I use the same app to log into FB, so I thought I'd log in to that account and see if I got the same notification. Well I didn't get the usual notification, so I then logged back into my main account and I now no longer get the notification ..... what gives??
I've logged into each account several times and even rebooted my phone just to make sure everything's sorted ..... but so far, no more notifications.
Does anyone have idea why logging into my other account would resolve the issue??