***Disclaimer: I am not a lawyer. I recommend that you speak with a lawyer about any legal questions you have.
I recently found the following article about trademark trolls and thought you would also find it interesting.
“Has a Troll Falsely Accused You of Violating Their Trademark? Here’s What You Should Do” by Angela Hoy: http://writersweekly.com/angela-desk/has-a-troll-falsely-accused-you-of-violating-their-trademark-heres-what-you-should-do-by-angela-hoy
For those of you who would like to do some research on your own, I have included a few more links which I believe you will find helpful.
“Trademark vs. Copyright Protection”: https://www.legalzoom.com/trademarks-patents-copyrights/summary-compare-trademark-copyright.html
United States Copyright Office: https://www.copyright.gov/
U.S. Trademark Law (January 14, 2017): https://www.uspto.gov/sites/default/files/documents/tmlaw.pdf
United States Patent and Trademark Office (Especially look under the “Trademarks” tab at the top of the page.): https://www.uspto.gov/