Go to 'Settings and Privacy' by hovering over your name (or clicking on mobile)
2. Go to 'Client Experience'
3. Click '2 - Customise Client Welcome Message'
4. At the bottom of the screen, click the toggle for 'Add your Welcome Chat Message'
5. Type in your message and click 'Save Changes'
Your client will now see this when they enter their client portal from the first time.