Hi there! I understand that when you press the Clear Scan app button on your device, instead of launching the scanner, Yahoo Mail opens up. Let me help clarify a bit so I can assist you better:

1. When you tap the Clear Scan app button, does it immediately open Yahoo Mail every time?
2. Have you recently installed any new apps or updates before this started happening?
3. Is Clear Scan installed from a trusted app store like Google Play?
4. Do other functions or buttons on your device work normally?

From what you described, it sounds like there's possibly a misconfiguration or a redirect happening on your Android device where the link or intent meant to open Clear Scan is instead routed to Yahoo Mail.

Let's try some common fixes first:

### Step 1: Clear defaults for Yahoo Mail app
- Go to your device's Settings > Apps & notifications > See all apps.
- Find and tap Yahoo Mail.
- Tap Open by default or Set as default (wording varies).
- If it shows it opens certain links or intents by default, choose Clear defaults.

### Step 2: Check Clear Scan app’s default settings
- Repeat similar steps for the Clear Scan app. Make sure it is set to open links or scans by default where applicable.

### Step 3: Reboot your device
- Sometimes a simple restart can reset app associations correctly.

### Step 4: Reinstall Clear Scan
- Uninstall Clear Scan, then reinstall it fresh from the Google Play Store to ensure no corrupted settings.

### Step 5: Check for unknown or suspicious apps
- Sometimes browser hijackers or redirect malware cause apps to open incorrectly. If the above steps don't help, scan your device with a trusted antivirus or malware detection app.

Could you try these steps and let me know if the issue persists? I can then guide you through more advanced options if needed.

Are you comfortable performing these steps?