[AC Question]

When I touch the "world" icon on my screen it immediately shows a porn site. Hoe can I stop this?

[my name1]

install antivirus and try to use custom web browser

[anon8380037]

also try to change the default home page in Internet - Menu - Settings, and clear History.
To be safe, go to Settings - Applications Manager - All - Internet, clear Cache, and Clear Data if you don't mind losing bookmarks and passwords. You can import bookmarks.
Also go to Accounts - Samsung - your account - and uncheck Internet syncing for a while.
Then if it returns as the previous poster said try to isolate an app that may have malware, or a launcher such as Go Launcher.

Malwarebytes, Lookout ad-aware, Avast are good, but I would uninstall them again once it's clean. It's not a virus, just either malware or someone changed your home page.