I see your image, it did upload correctly. The only fix for your left front caster is replacing the lower control arm. You could try and press in a new bushing if you wanted to save money, but have to do it precisely. It's usually easier to buy a new lower control arm from the dealer (as long as they match the lower online prices such as sparksparts.com, etc). Any time caster is the issue it's a damaged lower control arm or a worn bushing on that arm. Since it's not adjustable.
It's not that far out of spec, I dont suspect the sub-frame from being damaged. Plus you do have over 100k miles, so it's not that unheard of from wear/tear to cause this. Sorry but that's really the case here unless you can see some major damage to the arm. Plus people usually only have one person in the car (the driver) so it makes sense the left front would be worn more than the right front.
And welcome to cstc.