The slight softness when zoomed in more than 100% (your screenshot shows 200%) is antialiasing on a brush. It is used to prevent stepping of pixels on angled lines. If you don't want it at all, then use the pencil tool instead of the brush tool.
As for the pixelation when zoomed out, check in Preferences > General that Image Interpolation is NOT set to Nearest neighbour.
Davescm is right! I would ad 2 more things: - In the brush panel you have the "abstand" set to 5%, put it to 1% it will create less steps - Not realy relevant for screen work, but you should also create a 300ppi file instead of 72ppi