How to remove 'Data 0 / Min hold / Max hold' legends from plots ?

Hi

How can I remove the 'Data 0 / Min hold / Max hold'  legends which are always at the right side of QT GUI vector sink plots ?

I found a possible solution at

https://www.trondeau.com/blog/2015/4/9/qtgui-tools-and-tips

where it is told that

'In the GRC properties box under the Config tab for each QTGUI plotter, we can toggle the legend on or off. '

However, I do not have such a possibility in the config tab.

I am using GRC 3.9.5.0 in Ubuntu 20.04.4 LTS

Any ideas ?

Cheers, Kimmo