How to change the keys to control my iPhone with my braille display?

Hi again,
as you know, in this momnet I have an Actilino as Braille Display. There are some kieys to control the Iphone with it, keys, for example, to go to the line after, etc. but these keys are not confortabless. So, I would like to change them there is a way to change them with the Iphone, how can do it?. With the Mac, I know that thee is a way going in VoiceOver utilities, but when I arrive into Keyboard, I don't know how should I move with key in order to enter there and continues, because of this, i though that it would be a great thing to try it with the Mac.
Many thanks.
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María