Click on the box and you will see a small bell next to it. Turn on the little bell, and you will find the voice that you have talked with for a long time and open the other side to you. But there is a premise here, that is, you must have made your identity public. If you haven't talked for 3 minutes, or if you don't disclose your identity, you won't find each other. This also includes other people's praise and comments on you.
In the search bar at the top of the square, through keyword search, you can find the matching character tag moment. The search function is currently under maintenance. Note that soul does not support finding friends through mobile phone number and address book for the time being, but only supports signature and instant search.