Is there USA trademark or copyright law regarding using word titles seen on youtube to create their own logo? For example, if the title of a YouTube Video was "Avocado Sunrise" could one use those words to create their own logo for their own video promotion to be "Avocado Sunrise" but look different? Would an additional word need to included to be more unique?
"Avocado Sunrise" is probably a distinctive mark, and could perhaps be used as a trademark. Short phrases such as "Avocado Sunrise" are not subject to copyright protection at all, and so we can ignore copyright here.
(It should be noted that an existing logo, unlike a short phrase such as a title or slogan, will often be protected by copyright, and that using or imitating an existing logo will bring in copyright law. But the question does not suppose any such situation.)
Use of the mark as the title of a YouTube video might or might not interfere with someone else using the mark, depending on the content of the video. If it was advertising the same or a similar sort of product or service that might count as a prior use in commerce, and interfere in a new claim for the mark.
Please understand that trademarks normally are only protected relative to a type of product or service. Firm A could use "Avocado Sunrise" as a trademark for a variety of orchids, say, and firm B use "Avocado Sunrise" for a fruit drink, and firm C for a hotel chain, and firm D for a cleaning service, all without infringing on each other.
Also trademarks are limited by market area. Firm E could use "Avocado Sunrise" for a fruit drink sold only in California, and firm F could use "Avocado Sunrise" for a similar drink sold only in Florida, with no infringement.
Also, trademarks are protected separately in different countries. A protected trademark in Canada, say, has no protection in the US unless it separately qualifies for US protection. As YouTube is international, one would need to determine what countries a video was affecting to see what trademark effect, if any it had.
Also, only use of a mark "in trade" or "in commerce" is relevant to trademark protection. Use of "Avocado Sunrise" as the title of a video showing images of the sun rising out of the ocean to music but not promoting or advertising any product or service, and not itself being sold or rented, would not be 'in trade' and would have no effect on any trademark.
A mark that is similar but not the same may or may not infringe. If firm H had registered "Avocado Sunrise", could firm J use "Avocado Tulip Sunrise"? The test is whether reasonable consumers might falsely think there was a connection, might believe that Firm J's product came from Firm H or was endorsed or approved by firm H. If confusion is probable, the new mark is an infringement on the old one, otherwise not. This is a somewhat subjective test, of course.
In the US, simple use of a mark in commerce can confer a degree of protection. In many countries there is no protection at all unless a mark is formally registered with the government of that country. Even in the US, registration gets significantly increased protection.
If firm G used "Avocado Sunrise" as the title of a video which it sold, and promoted that with a YouTube video, say an extract, that would be a use of the mark in commerce. In that case, another firm could not market a different video under the name "Avocado Sunrise" to the same market without permission or a legal proceeding to establish that Firm G's mark was invalid.
In short the issue is a complex one, and use in a YouTube video might or might not be significant. It is often wise to consult a lawyer with trademark expertise before trying to establish trademark protection or to use a mark which someone else has used in a way that might possibly infringe. The exact rules in a particular case are fact dependent.