• Android
• Desktop

Android

To change the color for a contact:

1. Open the chat with this contact.
2. Tap on the contact name or number.
3. Tap on Color and choose a color.

To change the theme:

1. Open Signal.
2. Select the menu.
3. Select Settings.
4. Select Appearance.
5. Select Theme.
6. Choose Light or Dark. 

Desktop

To change the theme:

1. Open your Signal Desktop preferences:
     - Mac: Go to Signal > Preferences.
     - Windows: Go to File > Preferences.
     - Linux: Go to File > Preferences.
2. In the Theme section, choose Light or Dark.