They don't really explain that too well or I happily skipped the fuck out of it. I figured the top tabs were filters, to filter your search by what you're looking for so never really bothered to use them. Some games I used to play let you set multiple heroes but it would just be random which one people see so I figured thats what I was doing here too.
That said I eventually figured out the separate tabs were separate heroes alltogether and not just a filter, but I still rarely use it lol, most times peoples "Main" is their strongest and its what I use.