question Similar domains get TM issue or not ?

Hello
Everyone

Today i am researching about Trademarks, and i read all the pinned post in beginnner section
about trademark issue, but still having some confusion in my mind, regarding TM's which is not yet cleared.

So thought to ask u all experienced people.

My question is this :

1. As there is website called sound.com, so when i google keyword "sound" it shows
me all the sites related to sound, as i can see the differnt sites names as follows:

sound.com
online-sound.com
sounds.com
soundcom.net
soundonsound.com
pro-sound.com
theabsolutesound.com
bensound.com
etc.

So suppose the main site name "sound.com" has registred its trademark on the domain
in (1950) before every other site owner does.

So as these all rest sites using the keyword "sound" in them, do they fall under the category of
trademark infringement or not.

Bcse it is already registrd by sound.com owner in (1950)and its still LIVE and all remaining site owner also
running the same type of business content in there sites . So how these other site owners can use
his copyright word "sound" in there own domain name,

(As i know that if other site owners are running a differnt content in there sites, then there is no copyright or neither TM issue will arise.)

bcse they are all focusing on differnt content, but what if they are running the same kind of website contents.

So this is my main confusion here.
Can they use the keyword "sound" in there domain name or the owner of sound.com can file a complaint against all of them.


plz reply, i am waiting here.

Thanks
Oomeysh