You may already have resolved this, but if not, you need to grab the cert's Thumbprint (not footprint). Go to the cert itself, open its properties, and copy its thumprint, which is a long string of numbers and spaces. Paste that into the Proxy in QMC.
I have seen documentation saying to install your cert under machine account > Personal Certificates. I have also gotten advice to (a) ALSO put it in the trusted root certs and (b) NOT put it in the Personal certs but ONLY the trusted root. So I'm not sure what the final answer is.
Regarding SHA-1 vs. SHA-256, I'm not sure. Documentation indicates you should choose the same as what your cert is.