Generally, the presets are stored within C:\Users\User Name\AppData\Roaming\Adobe\Lightroom\
The other location that you mentioned (Lightroom Settings) stores the presets of Lightroom only when you have "Store Presets with this catalog" checked under Lightroom Preferences > Presets tab
Yes. When that option is unchecked, Show Lightroom presets folders opens
folder in the explorer, when checked opens
I was afraid to touch that checkbox before. The file Lightroom Catalog.lrcat is stored in
It is very important in case of move to reinstalled OS or to a new computer according to some webpages.
When you check the box " Store Presets with this Catalog" and then you click on Show Lightroom Presets folder, it opens different location : C:\Users\User Name\Pictures\ because the catalog saved to that place and the presets also get saved along with the catalog.
When you save the Preset in Lightroom not specific to catalog then it will go to the general location so it would available for use for all the catalogs you use in Lightroom.
Hope it helps.