The toggle button beneath the color of the pen your using (top left orange button) is to change the color of your screen, dark or bright. The circles with different colors are your color choices :) Click one and then your pen is that color. Click the eraser to erase, then write over what you want to erase, don't drag it! If the eraser isn't erasing, change the pen size. To go back to drawing, click the pencil in the top right corner. (Or just click a color and start drawing again) The toggle button, btw, is weird. The animation makes it shift positions. Lmk if I should remove the animation.
Credit goes to @rrath on scratch or R2 on YouTube :) (I changed some things but everything is mostly the same)
