The colour issue has been answered by D Fosse above.
One thing to add to this thread though is about pixellation. If your work is for screen use, then ppi makes no difference. It could be 1ppi or 1000ppi that is just a number stored alongside the image in metadata to calculate print size and is ignored completely for screen use. On screen all that matters is the size in pixels and viewing at 100% gives a true representation of that as 100% means 1 screen pixel is used to display 1 image pixel . If you are seeing pixellation on your screen at 100% there could be several causes:
1. Have you resized any objects/layers? Resizing downwards is unlikely to cause issues but upwards can do. Make sure you are using an appropriate algorithm such as Bicubic Smoother and not Nearest Neighbour.
2. Have you placed (embedded or linked) any images in your layer stack. That involves resizing and again the selection of an appropriate resizing algorithm is important.
3. Something I do see in your screenshot is that the brush anti-aliasing seems to be different on the left side of the gray brush strokes and the right. Without seeing the brush you used, that does look unusual. You may want to try resetting the brush tool, or closely at that brush for any setting that may be leading to that. I would also try a preference reset if neither of those work.
Dave