not sure what you want to change again, but you would click on Settings at the top of this page. Then scroll to the editable item you want to change. most are found under General Settings.
as to the color, you can highlight what you've written and click on the A next to the smiley above the typing box and choose the color you want. i don't know of a way to make that a default... you'd have to do that with each post. if Tartan knows a way to change the default, i hope she will jump in here.