Study in university or at? in the corner or at the corner?

In this instance, you would use in university. At is only used before specific terms such as "I am studying at Harvard" or "I am studying at Williams College."

For the second question, context must be applied. If you are talking about the corner of a room, in should be used. However, if you are talking about the corner of a sidewalk or street, on or at would be correct.

I hope I helped!

IN the corner if it is where you are putting something that is closed - like in the corner of the page. AT the corner is if you are talking about a location - like the corner of a street.

AT - if you are at a place, you might not be in it.  You might be at the University to see a show.  You will be IN University if you are studying as a part of your University studies.