What is the white triangle in the upper right corner of my screen?

I guess it depends on what triangle we are referring to.

The white outline arrow, (could be viewed as a triangle) next to the clock icon, is the Geofencing icon as explained by Asher.

The gray triangle in the very top right corner of the screen, is very likely from the background image being used.

I see no other triangle, nor why it would have any relation to the clock app.

The Triangle in the Upper Right corner in the screen Indicates that your iOS device is using Location Services!

About privacy and Location Services in iOS 8 and later - Apple Support

Go to Settings -> Privacy -> Location Services -> System Services -> Scroll Down and it is explained what each symbol means:

That's not the issue the OP described.

And that's not a triangle.

Look at the upper right corner.

Giulio

Phil0124 wrote:

I see no other triangle, nor why it would have any relation to the clock app.

Phil, let me point out that I asked the OP to open the clock app (which has a black background) because I intended to demonstrate that if the triangle wasn't visible, she should feel comfortable. The triangle wasn't related to a problem in her screen or pixels, but only in her background picture.

Unfortunately I had to go away, and I couldn't wait for her answer, nor better explain my "strange" experiment.

Regards

Giulio

Open your clock app. Is it visible there? in the same place?

Regards

Giulio

There's probably something there that gets cut off at the corner and appears as a triangle though in the picture it may not be.

I hope you read my reply to Phil, so that you can understand my attempt.

Regards and best of luck.

Giulio

Maybe it is in the background photo. Have you tried changing the background photo?

ProustGiulio wrote:

I hope you read my reply to Phil, so that you can understand my attempt.

Regards and best of luck.

Giulio

I have read your reply. I understand what you were doing.

Thank you, Phil.

Have a nice day.

Giulio