Ender 3 v2 bed temperature changes after print start

Hello folks! This is my 1st question. I have some poor first layer adhesion and found in https://www.wevolver.com/article/pla-bed-temperature-print-temperature-settings that maybe bed temperature setting is somewhat low. It was at the original 60°C since I started using the printer, so I tried to increase it in Control> Temperature> Preheat PLA settings> PLA Bed Temperature to 65°C, then Save PLA parameters.
So far so good, bed heats up to 65°C but as soon as the real printing begins temperature setpoint drops suddenly to 60°C. I tried setting this temperature at Control> Temperature> Bed Temperature but it didn’t work.
There are so many things to set up I am probably doing something wrong.
I’ll be very glad to hear any help from you.

Temperature is a bit of trial and error. 65°C is a bit high, the glass transition temperature for PLA is around 60°C so you might find problems of corners lifting. I prefer to run between 50-55°C. Biggest thing about adhesion is getting the Z offset just right. Manually set it to the thickness of a piece of paper and then drop it by 0.05mm increments, best to print a skirt for this so you can see the squish before the actual print.

Thank you, @Bonfireman for your kind reply. But I still need an answer to how to set bed temperature and keep its setpoint unchanged if I want to try 55°C for instance.
With my present knowledge I’m stuck with 60°C no matter what I dial in configuration menu.
Nevertheless, you are absolutely right in respect to Z clearance. I did a thorough calibration of all four corners to 0.1mm using a stainless steel thickness gauge, and even with temperature at 60°C the job printed flawlessly.
I’m still looking for help in changing ed temperatur setting.

What slicer are you using…?

Wouldn’t the settings in the slicer override any other settings you try to set…?

Good question, @jimandyen. I have no idea, I use the Ultimaker Cura V 5.6.0
I’ve assumed the slicer would not change anything temperature wise, only dimension wise.

Under the material tab you set the material and bed temperature. That’s the way I have used it to set the temperature, similar to any other slicer that I have used.

Hmmm… that’s probably the problem. I never had changed more than infill density!
Thank you so much!