What view are you using. Do you have it in separated mode or are you using a smaller screen? The Crop to opaque button is quite long in german so it may just be slightly off the toolbar. There should be a double arrow on the context toolbar to indicate that there are some more options. If not would you be able to attach a screenshot of what you are seeing?
The crop to bounds option should reset the crop tot the entire size of the timage, including transparency. So this will not do much until you change the size of the crop from it's initial state