How to use axe?

[420Hero]

No option for mapping to my keyboard and tried every keystroke... will not let me use axe to smash crates - tried the middle mouse button too. It works when the screen prompts me to use it but cannot randomly smash a crate by pressing middle mouse evfen though I have three of them...help game unplayable now

[bigfish821]

mouse 4 button( click on the scroll thing)

[bigfish821]

if you need help with commands, there is a lot of useful info when you press J in one of the sections