For information about editing your business profile's name or username, please check out this article.
When you sign up for Venmo, we strongly recommend creating a username that’s unique to you and easily recognizable. This will make it easier for your friends to find you on Venmo!
If you don’t remember what your username is, you can always check and update that whenever you’d like. If you’re on the old version of the Venmo app (with the ☰ icon in the top right), tap the "☰" at the top of the app. Your username will be displayed near the top. If you’re on the new version of the Venmo app (without the ☰ icon), go to the “You” tab by selecting the single person icon 
. Your username will be displayed near your profile picture.
To change your personal account's username in the app, head to your Settings → Edit Profile, then type in your desired username in the correct field. Please note that your username will need to be between 5 and 16 characters (no special characters other than - and _ ).
From the web, click here or select "Settings" then "Profile" from the left side of your screen to view or edit your username.