You can set the desired default in Safari ... I solved this same issue via a cache link in an e-mail. Open an e-mail containing a link to any cache, press & HOLD your finger on the link and a list appears asking you to choose in what app to open the link. Select Safari rather than geocaching app and you’ll find next time the “open in geocaching” link in L4C opens in Safari every time. Hope this helps a frustrating feature of Apple!