How to show notifications on iPhone screen?
Apologies for what sounds like a stupid question, but I'm genuinely having trouble with it. I keep accidentally discovering that I received app notifications days previously, but because the default tone is usually inaudible and nothing shows on the phone screen, I only find them by accidentally opening the Notification Centre. It would be useful to be able to hear them arriving in the first place and to have a flag on the screen, otherwise there's not much point setting them.
The notifications are supposedly set in the Control Centre to show as a list, but they never appear on the screen, only the Notification Centre (which for some reason is hidden, so you have to remember to check it manually). Nor does it appear possible to change the notification tone from an apologetic "ching" on a mouse's triangle, only audible in conditions of total silence, to something a bit more prominent.
I often receive two-factor ID codes from financial institutions, so obviously I can't allow message previews to be shown on the Lock Screen—that would mean any fraudster who stole my bank cards and phone could easily empty my accounts without needing to be able to unlock the phone or work out my PIN numbers. Is this potentially the cause of the problem? The phone is set to show message previews once it's unlocked, but they still don't appear on the screen.
I'm sure this must be something childishly simple, but I can't find my way round it.
[Re-Titled by Moderator]
iPhone 8