Please use the explode suggestion as a TEMPORARY stop gap measure. Explode is s dirty word in Civil 3D.
As was already mentioned you will need to learn how to use styles. If you create your drawing using the "_AutoCAD Civil 3D (Imperial) NCS Extended.dwt" there are many decent styles in there to start from. You can also drag and drop styles from the template to your drawing. And I think you can insert your drawing into the template but I have not tried this personally.
Now as far as manually editing contours your going to want to stop thinking that way with Civil 3D. Contours are a representation of the actual surface model. There are tools to modify the surface by adding points, smoothing the surface, etc. that will affect the appearance of the contours.
Your other option is not good, explode to polylines and edit them. Once you explode the surface all links the surface are lost. For example, profiles of the surface will disappear.
I have to admit it is difficult for some people to accept small zigzags or other anomalies in the contours. What I say to those people is, do you want to make a profit on this project or do you want me to take 5 times longer to get it done so it looks perfect. Or something to that affect.
Jeff Paulsen
Civil 3D 2020.4 | Win 10 Pro N 64-bit
Xeon W-2223 @ 3.60GHz, 32GB Ram | NVidia Quadro P2200