Iphone brightness setting changing on its own

[DanHumphreyIsA]

My phones battery drains pretty quickly, so I have been keeping it the brightness setting to a minimum for the most part, as this seems to extend the battery life

I dont notice the screen suddenly flash or anything so I think it moves up gradually, but when the battery suddenly starts draining again, I check the setting and its at maximum brightness. Anyone had this, do you know how to stop it?

you can switch off 'auto brightness'

Go to settings, then display and brightness and turn off auto-brightness. You can then swipe up from the bottom of the screen if you need to brighten or dim it manually.