Here is something you may not know. Facebook keeps a record of all your searches. If you are concerned about your privacy, you can follow these simple 5 steps to delete your search history.
These steps work on a desktop or notebook computer. I haven't tried on a cell phone or with a FB app:
Step 1. After you are logged into Facebook, go to your profile page by selecting (click) the link that shows the name of your account.
Step 2. Click the Activity Log button.
Step 3. On left side of page is a list of links. One of the links is labeled "More" - click on it and an expanded list of links will appear. Select the link that says "Search."
(4) At the top of page will appear a link for clearing all searches or you may delete individual searches by clicking on the symbol of a circle with a slash through it. This symbol appears next to a lock symbol.