Or, for the sake of using what ya have, do a basic scrn shot even on 4k
I use ctrl-alt-prntScrn to only take a scrn of the active window.
Then open Paint and paste (ctrl-v) it in there. Crop to your heart's desire.
Using Paint, then save it in a format of your choice.
Then, take a look at it. If it is fuzzy, I would go for what many have shared and try another prnt scrn app.