Logo is too small on my invoice - how to we make it larger. I already selected the L option but same result - can anyone help?

You can create more than one invoice style; it will always default to the one you have set but on the bottom of the invoice screen you can select the invoice style you want to use.

I believe you should be able to select your logo outside of QBO and increase the size, then save it with a new name to use in QBO.