Balances and expenses

How can I manage a friendship or group with multiple currencies? I accidentally settled up - how can I undo this? Can you explain the "Totals" screen? What are different ways I can split an expense? What does it mean if I'm 'fully settled up' with my friend? How can I double check my balances? How can I manage recurring expenses? What is Simplify Debts? Can you help me understand my dashboard balances on the web app? How do I add a refund or reimbursement? How can I restore a deleted expense?