when I make brush strokes, the strokes do not appear.
I'm guessing that you're on Windows, and not on Linux. This happens with a buggy Intel display driver. See https://docs.krita.org/KritaFAQ#Krita_starts_with_a_black_or_blank_canvas_and_nothing_changes_when_you_try_to_draw.2Fshows_a_black_or_blank_screen_on_my_Windows_system_with_an_Intel_GPU and also
https://krita.org/en/item/angle-and-windows-ink-a-new-test-version-of-krita-for-windows/ for test packages that used direct3d on windows instead of opengl.
*** This bug has been marked as a duplicate of bug 360601 ***