A friend has no Search function on the main menu
I have a Roku Ultra, and along the left of my Roku screen is: Home, What to Watch, Live TV, Featured Free, Sports, Weekly Trivia, Streaming Store, Search, Settings.
A friend just bought a Roku Express 4K+, much smaller and cheaper than what I have, and she only has three options on the left: Home, Streaming Store, and Settings. So she doesn't even have a Search bar which is what I use to search and then install different TV apps.
Why the difference between my interface and hers? Without a Search option, she can't even find Amazon Prime Video or several other streaming apps that she'd like to install.
Generally, if you are located in the US and find that you are missing the "Search" menu item, usually indicates that the Roku account may have had an issue when it was created. (regional issue). Some regions do not have a Search feature on the device.
If your friend is also in the US, likely she will have to Factory Reset the device and try to setup a new Roku account (use new email address). Make sure to disable any VPNs or anything else on a network that may hinder Roku's ability to determine where the device/account is located. Can even try using a mobile hotspot (if available) if having trouble with the home network.
In order to factory reset, press and hold in reset button for 30+ seconds or use the Factory Reset option from Settings/System/Advanced System Settings/Factory Reset. This will affect any subscriptions that your friend is subscribed to if purchased "through" Roku. (using Roku Pay).
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There are some settings under Settings/Home Screen on both devices that the user can enable/disable from appearing on the Home Screen, but the Search is not one of them. (just in case something else is showing on yours, but not hers).