Have you tried a simple" Hey X, let me show you this cool trick about channel?"

Why do you think his age is to blame? Maybe it is something wrong with the application itself, that makes it generally not easy to see in which channel you are typing. In such applications I have noticed that usability often takes a backseat. They add silly things like emoticons and animations, but don't even consider whether the application is obvious and easy to use.

@Brandin Teams is somewhat ... well some like it, some don't. But I think OP is referring to Coworker's inability or unwillingness to "dive" into the workflow and adopt. This does not have to but - from own experience - is more likely to happen in "older" people. With incredible exceptions! That is in now way meant to be age-discrimination. I even experience that in myself, getting older. I do sometimes have to actively force my mind to "yeah, let's have a look that cool fancy new stuff". And I'm not anywhere near 60.

The statement about the age of the coworker is irrelevant. As a "gentleman in my 60s" I've been using such methods of communications for years w/o problem. It's also as offensive as saying "as an Indian gentleman..." or "as a woman..." would be.

"Like many in his generation, he is not accustomed to this style of communication." - This is ageist.

As @KillianDS says, this does sound like a lot of channels for a small company. Are you trying to use chat channels as an issue tracking system?

His age clearly has nothing to do with it, i'm only in my 20s and i can't even begin to visualise the weird flow you guys must have going on needing that many channels for 15 people.

@Donald it is a clear cut fact. The co-workers age may give a (partial) explanation for their ineptitude at using this medium, as it would require them to have made an active effort at some point to get familiar with this mode of communication. (Whereas for most co-workers in, say, their 20s, this is is natural/obvious.) It does not seem relevant to the question though.

@Servaes - That particular statement would actually be considered a stereotype, not a clear cut fact. It's also a stereotype that happens to be incorrect in many cases. It certainly happens to be incorrect for this particular user.

@Donald It is not a statement about any particular person, it is a statement about a trend in a certain group of people. It is not a stereotype because it explicitly does not claim to hold for the entire group.

I am still deeply offended by the ageist statement

Nothing personal, but this is the perfect setup for "Ok boomer." ;)

"Like many in his generation, he is not accustomed to this style of communication." That is a stereotype... It's also probably wrong - bulletin boards and instant messaging have been around 30 years or more, so lots of people of that age are probably familiar with it. And I see plenty of young people (20s and 30s) who do the same as this guy in Teams environments.

Have his boss teach him, and then tell him this is how he is expected to use it.

"I have in the past made suggestions trying to help, but they haven't worked" - do you know why?

Perhaps this person isn't really aware of many channels. It wouldn't be a big deal to explain that to him. Did you try that?

@Donald wow is there even a negative word about stating that someone is in an age that makes it more unlikely to have much experience in some technology? Is that helpful in any way?