How to open in Safari — iPhone:

Option A (easiest):
1. Look for a share icon ⬆ or box-with-arrow 📤 at the top or bottom of your screen
2. Tap it → scroll down → tap “Open in Safari”

Option B (from Mail):
1. In the email, press and hold the attachment filename
2. Tap “Share” from the menu that appears
3. Tap “Open in Safari”

Option C (from Files app):
1. Find the downloaded file in your Files app → Downloads
2. Press and hold it → tap “Share”
3. Tap “Open in Safari” — not just tap to open

How to open in Chrome — Android:

Option A (easiest):
1. Tap the ⋮ three-dot menu in the top-right corner of your email app
2. Tap “Open in Chrome” or “Open in browser”

Option B (from Downloads):
1. Open your Files or Downloads app
2. Find the file → long-press it → tap “Open with”
3. Choose Chrome from the list