Hey, thanks for the feedback and question! To use different tools, use the scroll wheel to select different slots in the toolbar on the right side. The selected slot will be highlighted in yellow, and it's contents will be the tool/item that you are using/picking up. Also, to break trees, aim for the bottom section since their hitbox is the same when breaking it as it is when colliding with them. That is another thing that could be unclear.
I'm glad you mentioned that part of the instructions since I forgot to include scroll wheel controls in the menu, and I will make sure to change that for the next update. I will also look into why the antivirus needed to be turned off to play, but to my knowledge, antivirus software commonly doesn't like .exe (application) files in general, especially when the publisher is unknown as is the case for Feed-X. That is most likely the reason for needing to turn it off. The file is unknown because there is a special way to tell the file what who the publisher is that I didn't do for the Feed-X application.
Thanks for the feedback and I hope this is helpful.