Jason here from Shopify Support.
Thank you so much for the screenshot. I'm not quite clear on what you mean by edit your answer. Are you referring to the line or the content below?
The line is in your post naturally dividing between your answer and your signature. You have the line here. The content below is your signature, which you have set up already.
If you're referring to the dotted break line but inside your post, you can type out "-". Since the rich text editor isn't the same width as the post, you can use the Preview function at the top to see if the "-" overflows to the next line and remove the excess "-".
Rather than leaving your store URL in your answer post, I recommend you craft a promotional statement in your signature area, which already contains your Store URL. Also, the signature is in the post always. Feel free to edit it to the way you see fit. It can be something like "A proud owner of www.8bluetech.com. Come check out the Best Qi Wireless Chargers for iPhone/Android!". Don't forget you can hyperlink your store URL! This not only allows the fellow merchants and experts to focus on your answer while still promotes your store, but It also prevents the post from looking like a spam post.
If there’s anything else I can help you out with, please don’t hesitate to reply back and I’d be happy to help out!
All the best,
No problem at all. Glad to assist! If you have any questions, don't hesitate to reach out to the forums. We're always here to help. Wishing you great success with your store!