So this might seem like a fairly straightforward tutorial but for the user who is beginner/intermediate this might help! I spent a lot of time and a lot of swearing to work this out and I thought I'd share for those in the future.
I wanted a button (and not one of Construct's pre-made ones) to mute sound and I wanted it clearly show when sound was on and when sound was off, so I created these on illustrator:
Using the Audio toggle silent function, I was able to get the functionality working but I couldn't work out how to change the image, until I finally worked out the answer: GLOBAL VARIABLES!
Here's the event sheet:
It turns out, there is a very good tutorial on this already with an good explanation and other suggestions: https://www.scirra.com/tutorials/158/veryvariable-toggle-between-two-states (I wish I had found this sooner!)/i[https://www.scirra.com/tutorials/158/veryvariable-toggle-between-two-states]
If you want to see this button in action, check out this bad boy: http://bit.ly/heyshirley.
Hope this helped!