The big bump on the inside of your foot by your big toe base is the first metatarsal head. Tradition had the cleat center being placed directly at this point when changing fore/aft cleat position. Frankly, we picked this because it was easiest to find. Anatomically, it has some drawbacks as there are two small bones under this ball of your foot called sesamoid bones (because they look like sesame seeds). Placing the cleat center of effort (there may be a small raised marking on your cleats as lightly highlighted in blue below) underneath these can lead to tingly toes or even “hot foot”.
Sliding your cleats backwards at least 5 mm behind the first metatarsal can help ease this pain.
Lateral cleat position is all about a comfortable stance. You’d like your knee’s pressure to be pushing straight down onto the pedal. This will lead to better knee health as a knock-kneed or bow-legged position stresses a joint adapted only to one plane of movement.