Keyboard Setting

Hi All

My first ever post on this forum so go easy :)

I have a Macbook Pro with a Spanish Keyboard layout, I have changed this to Australian but now some buttons are not working as expected, for example, if I want to use the "+" button, the button on the keyboard does work, I have to press shift and then the button as outlined in the image with the yellow arrow.

Is there a way I can fix this? I have Australian keyboard active in the settings and the language region is also set to Australia. Im stumped.

Any Ideas?