That's not how the fediverse works.

Your account can only be used from the instance it was created on. Your instance is connected to other instances in a way that allows you to interact with their content, without ever leaving your instance.

You can use your account to go anywhere in the fediverse, but you can't use that account to access the fediverse through any other entry point, or interact with every feature of every platform. All the platforms speak the same protocol, but don't necessarily have parity in terms of features.

It's like you're standing in one spot, and can look in any direction, but you can't move. You can see everything, in the way it looks from that one spot. If you want a different perspective, you need a new spot to stand on (a new account on a different instance/fediverse platform).

As an example, because you added @kde to your post, I can see it on the KDE community on Lemmy, and this comment was created on a Lemmy account. As a Lemmy user, I can't follow you, or see any of your posts that don't mention a Lemmy community.

To interact with all that stuff, I'd need to use a Mastodon account on a Mastodon instance, to get the full picture.