Connect your social accounts
Open Menu, then GROWTH, then Social Studio, then the accounts screen, and tap Connect.
Enter your handle for each account you post to. The screen explains why: add the accounts you post to so they show up as options in the composer.
Be aware of what this does and does not do today. The app says these will be linked to auto-posting when that goes live, and a scheduled post publishes automatically once your accounts are connected. Until then, treat Social Studio as drafting and scheduling rather than posting.