I was wondering similarly recently. I just discovered a great copy-paste solution in the following thread by Laurent.
https://qelectrotech.org/forum/viewtopic.php?id=2571

Basically, you open an existing project in a text editor and copy any settings you need from between the <newdiagrams>...</newdiagrams> tags and paste to a new file saved with .qet extension. Now continue in QET

I was using QET very much these last holidays and created a lots of drawings.

I fiddled a lot with the auto numbering capabilities of QET.

First of all, I find it annoying, to define a set of auto numbering schemes for each project I begin.  It would be more efficient, if you could save those rules as part of your program preferences.

Is there any chance, to save them in the program preferences, e.g. a personal config file?

Next, I defined ca. 15 rules for elements only.  I tried to define a kind of hierarchical rule names or at least alphabetical or numerical names.  None of that worked out.  When inserting a new element and I use the drop down menu in the "Auto numbering selection" panel, they are presented in random order, which makes it hard, to find the desired rule fast.  This is prone to errors. :-(

Than I do have a feature request in mind, but I am not sure, if this due to my crooked mind.  I am an mechanical engineer, not a trained electrician.   So please bear with me.

I think I have noticed, that the labeling for e.g. fuses are as follows (at least in Germany).  In a cabinet, there are often more than one level stocked on each other.  The fuses in the lowest level are labeled 1F1, 1F2, 1F3, ... whilst the fuses in the next level are labeled 2F1, 2F2, and so on.

I was not able, to insert a variable for the level indicator.

Imagine, that when you select a fuse related numbering scheme, an additional box would get activated.  It presents the level-number, you most recently selected, plus offers the +/- switches, to increase or decrease the number.  Depending in that prefix number, the counter is reset accordingly.  Wouldn't that be nice?

One more thing, that I was not able to get fixed by myself. 

I draw my schemes to present the logic of any circuit.  Therefore, a plan of a cabinet often shows switches, motors and other elements, that are not build into that specific cabinet.  This kind of drawing style makes the path of the current/conductor complete, so you get the logic behind it.

In case, an external component is presented in such scheme, I want the label to contain the plant and/or location of that element to be shown, to make clear, that this belongs not to that cabinet in question.  I tried to use a rule like

=%{LM}+%{M}-M%{sequ_1}

and hoped, that I was able, to override the plant and location for that element, when editing its properties.  (The Selection Properties PopUp offers inputs for plant and location as well.)  But this specific information is not observed.  Instead the global values entered in the project properties are used. :-(

Is there any chance, to change this?

Have a fine day