I sometimes leave the machines set at a higher weight than I can handle so people don't think I'm weak
That sounds dangerous, why?
I want people to think that I am breaking a sweat when I lift.
Faking how much weight you lift in the gym is deceitful to others and wrong. Stop worrying about how others perceive you and focus on your workout instead.
Lifting for me is to break a sweat and have fun. It doesn't have to be perceived as something else.
If you lie and then forget and get hurt you will regret it. Nobody else cares they are there to work out and lift then go home. Please don't hurt yourself for vanity.