Yes I did what videos say and it heats up past the 78 degrees .I have a 120xl elos and I know it’s too big but I have a 250 coming tomorrow with a inkbird from brs.
Typically although not fancy at all these heater are solid. First make sure that the water is up to the water line on the heater. If so then the way I have always done it is set the heater to whatever temp (78), the next day check the water temp with a few different thermometer to find the average temp. If not matching with the heater temp the move the read arrow so it points to the number that corresponds to the water temp. If you do this and the heater doesn’t maintain that temp then you might have a bad heater . The heater should be checked for calibration quarterly.