Thank you for the feedback! It's been a while since I've messed around with this project.
I'm not sure what you mean about the zero being really small (see the below image). However, I do see that the plus and minus seem to be missing from the font. That is something I can for sure fix.
On your android points. Do you use the keybinds on Android? I am just realizing that for 99% of people it is unlikely that someone will have a keyboard for their android device so it might be best to just disable the menu altogether for the android version.
I think I have found that stuck sound in the keybinds menu before... but since it is not that critical, I don't think I spent any time tracking it down. As for frogs disappearing. As long as they reappear upon hitting the default button, it doesn't seem too much of an issue to me, though obviously annoying.
You are right about no way back to the menu for android... There's no escape key on phones... is there. I should add one.