Fairyy~~ is referring to using Icon Packager (IP)=
Link. It has a 'rebuild icons' option in setting.
There may be a way to rebuid usng Windows, but I wouldn't know it.
There is a way to turn off the background around your icon text, unfortunately I don't remember the steps and I'm at work on a pretty much locked down system.
There have been one or three posts regarding icons and pixelation but the majority of forum posts are found at the Wincustomize site which my employer has blocked.
I suggest doing a search for 'icon' & 'icons' to start, and focus on the 'more' tabs under general and stardock support. I believe you will find the answer to both your issues.
hmmm... first try this - go to 'my computer' then on the left click 'view system information', 'advanced' tab, the 'settings' under 'performance', 'visual effects' tab, scroll the list see if the options for "smooth edges of screen fonts" and "use drop shadows for icon labels on desktop" are checked...that may take care of the background showing around text.