which AI rotovap are you using? This is the control panel off the 2l, I don’t imagine they got much higher tech on the bigger ones.
behind that label is most likely one of these
https://www.google.com/search?q=PID+controller
pushing and holding the set button for 3 seconds might drop you into programming mode. where the temp limit it set. (based on dozens of these I’ve interacted with).
chances are there is a LOCK function you need to unset first.
AI might tell you this. more likely they won’t. if they won’t, using the manual from another controller will probably give you enough clues about the glyphs displayed to navigate the interface. just remember to note the settings on anything you change. 
and yeah, beaker on a hotplate or in your mantle will work too.
I don’t recommend the above if it’s outside your comfort zone. I’ve beat my head against the controller on my still for about 20min before I found where a minion had set it to cooling mode rather than heating mode, so it was turning OFF the heating element to try and warm the still up!