Ender 3 Pro, measured temperatures don't match what the machine says

Hoping someone can help me here. I have an Ender 3 pro. Just recently I installed a new 4.2.7 main board and CR touch. I also added a new PEI build plate. Then I downloaded and installed this firmware from Creality Cloud... (Ender-3 Pro Marlin2.0.1 - V1.1.2 - ALT - TMC2225.bin). I don't know if this problem started after installing those upgrades or not, but I was curious about my temperatures because I've had some prints come out warped (those actually happened before the upgrades). Anyway, I have an optical temperature sensor, so I set the bed at 45 degrees up to 80 degrees in 5 degree increments. At 45 degrees, the actual temperature was 38 degrees (7 degrees low). Then at 80 degrees, the actual temperature was 67 degrees (13 degrees low). I did the same for the nozzle starting at 200 and up to 260 degrees. At 200 degrees, I measured the actual temperature at 185 degrees and at 260 I measured the actual temperature at 260 degrees. I can't find anywhere in the machine where I can calibrate the actual temperature (not just the PID, though that doesn't seem to be available in the menu from the new firmware). Does anyone have any idea what I can do about this? Is it a common problem? Or perhaps an issue with the firmware?Any thoughts or help would be appreciated. I'm just completely at a loss for what to do. Thanks in advance!