It's not just the phone. I listed on my laptop/computer and for FP listings, the b.o. option is the default.I too have noticed that Best Offer seems to be the default when using the app on some devices. A "best offer" appeared on my listing and I did not even notice it. I received an offer and declined it (politely), and edited my listing to remove the Best Offer option. My item did not sell, and I relisted it but didn't check it. Again the Best Offer option apparently appeared and I did not notice it until I again had to politely reject an offer. This is annoying. I believe I relisted the item from my phone. Got to check everything.