To change your language settings on Facebook, follow these steps:

1. Log In: Open your web browser and go to the Facebook website (facebook.com). Log in to your account if you’re not already logged in.
2. Access Settings: Click on the downward-facing arrow in the top right corner of the Facebook page. This will open a dropdown menu. From the menu, select “Settings & Privacy,” then choose “Settings.”
3. Language and Region: In the left sidebar of the Settings page, click on “Language and Region.”
4. Edit Language: Under the “Language” section, you’ll see your current language preference. To change it, click on the “Edit” link next to your current language.
5. Choose a New Language: A popup window will appear with a list of available languages. Scroll through the list or use the search bar to find your desired language. Click on it to select it.
6. Save Changes: After selecting your new language, click the “Save Changes” button.
7. Confirmation: Facebook will ask if you want to translate the Facebook interface into the new language. You can choose to “Translate Facebook” or “Not Now” if you want to keep the interface in your current language.
8. Password Confirmation: For security purposes, Facebook may ask you to enter your password to confirm the language change. Enter your password and click “Submit” or “Continue.”
9. Language Changed: Your Facebook language should now be changed to the one you selected. You may need to refresh your browser or restart the Facebook app on your mobile device to see the changes take effect.

To clear your Facebook search history, follow these steps:

1. Open Facebook: Log in to your Facebook account using a web browser or the Facebook mobile app.
2. Access Activity Log: On the web, click the down arrow in the top-right corner of the Facebook page, then click “Settings & Privacy” > “Activity Log.” On the mobile app, tap the three horizontal lines in the bottom-right corner, scroll down, and under “Settings & Privacy,” tap “Activity Log.”
3. View & Manage Activity: In the Activity Log, you’ll see a list of your recent activity on Facebook. To clear your search history, click or tap “More” on the left sidebar, then select “Search History.”
4. Clear Search History: On the web, click “Clear Searches” at the top right of the search history. On the mobile app, tap “Clear Searches” at the top of the search history.
5. Confirm: You’ll be asked to confirm that you want to clear your search history. Click or tap “Clear Searches” again to confirm.

To delete Facebook messages, you can use the Messenger app or the Facebook website. Here are steps for both methods:

Using Facebook Messenger (App):

1. Open Messenger: Launch the Facebook Messenger app on your mobile device.
2. Select Conversation: Tap on the conversation that contains the message(s) you want to delete.
3. Delete a Message: To delete a specific message, tap and hold the message you want to remove. You should see options like “Delete” or a trash can icon. Tap “Delete” and confirm.
4. Delete an Entire Conversation: If you want to delete an entire conversation, open the conversation, tap the contact’s name at the top, and select “Delete.”

Using Facebook Website:

1. Log In: Go to the Facebook website and log in to your account.
2. Open Messenger: Click the Messenger icon (it looks like a speech bubble) in the upper-right corner.
3. Select Conversation: Click on the conversation containing the messages you want to delete.
4. Delete a Message: Hover your mouse over the message you want to delete. You’ll see three dots (…) on the right side of the message. Click these dots and select “Delete.” Confirm the deletion.
5. Delete an Entire Conversation: To delete an entire conversation, click the gear icon (⚙️) at the top of the chat and select “Delete.” Confirm the deletion.

Remember that when you delete a message or conversation, it will only be deleted from your account. The other person(s) in the conversation will still have their copy of the messages unless they also delete them.