Hello, do You know wany ways on how to change topic or post author/username in PHPBB forum?

In my case i was not able to change it by moderating the topic. But what worked is when i

1) loged in as admin and then
2) on the bottom of the post which username i wanted to change are icons for post Editting, Warning user, Deleting post. And there is also button with questionmark (?) icon.
3) When clicked question mark icon, scroll down and one can change post/topic author username (switch post/topic author)