ImageJ scale bar: manually changing one of the values set by a macro while leaving the others as is

Question

I have a set of macros that allow me to select the magnification of images taken with a microscope, set the scale and add a scale bar with predefined appearance settings.

These macros look like this and are stored in a file called "StartupMacros.txt" in the macros directory of ImageJ:

macro "Scale_Leica_010x_whitebg [1]" {
    run("Set Scale...", "distance=3021 known=1000 unit=µm global");
    run("Scale Bar...", "width=500 height=39 thickness=10 font=70 color=Gray background=None location=[Lower Left] horizontal bold overlay");
}

macro "Scale_Leica_020x_whitebg [2]" {
    run("Set Scale...", "distance=4260 known=700 unit=µm global");
    run("Scale Bar...", "width=200 height=39 thickness=10 font=70 color=Gray background=None location=[Lower Left] horizontal bold overlay");
}

Sometimes I need to change the appearance of the scale bar depending on the image (e.g. the position of the scale).
However, when I go to the Analyze > Tools > Scale Bar menu, all the settings are reset to their default values.
So if I only want to change the position of the scale bar, I also have to change all the other appearance values (colour, font size, ...).
I would expect that when I open this menu, the values predefined by the macro would already be pre-coded in the corresponding fields, so that I only need to change the value of the position, for example.

Any ideas on how to do this?