DOCS: Create Switch-to-light-or-dark-mode.md

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docs/articles/new-expensify/settings/Switch-to-light-or-dark-mode.md

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+---
+title: Switch to light or dark mode
+description: Change the appearance of Expensify
+---
+<div id="new-expensify" markdown="1">
+
+Expensify has three themes that determine how the app looks:
+- **Dark mode**: The app appears with a black background
+- **Light mode**: The app appears with a white background
+- **Use Device settings**: Expensify will automatically use your device’s default theme 
+
+To change your Expensify theme,
+
+{% include selector.html values="desktop, mobile" %}
+
+{% include option.html value="desktop" %}
+1. Click your profile image or icon in the bottom left menu.
+2. Click **Preferences** in the left menu. 
+3. Click the **Theme** option and select the desired theme.
+{% include end-option.html %}
+
+{% include option.html value="mobile" %}
+1. Tap your profile image or icon in the bottom menu.
+2. Tap **Preferences**. 
+3. Tap the **Theme** option and select the desired theme.
+{% include end-option.html %}
+
+{% include end-selector.html %}  
+
+</div>