Some Windows Open And Are Too Small To Read?

I have a new Dell Inspiron 15 series 7000 which can with Windows 10. I am still learning my way around 10 and I'm no computer wiz. Some windows which open are very tiny. I am not referring to the size of the icons and text as it appears in some windows. Most windows are fine but a few are hardly legible. This is not browser specific, as one of the places I encounter it is when I do a Remote Desktop Connection. I have tried changing all of the display settings I can find but these adjust things across the board and once I get the small stuff large enough to see, much of what I do becomes way too large to fit on the monitor and is a real pain.