Hi.  I'm using Ellipse bezier curves to create a form, and then adjusting the thickness with the Scale option (i.e. 0.15).  I have a couple of different scalers for different elements.  When I reopen a file and touch (i.e. move) as element, it suddenly changes the scaler to the current setting.  How do I lock the scaler so lines don't update with future changes to other elements?  It's driving me up the wall, and worried when I send file to printers, things will have been resized/reformatted.

Thanks

I'm not sure what you're describing here. Are you using the ellipse tool [e] or the bezier tool [b]? What do you mean by "create a form"? Which "thickness" are you adjusting? What is the "Scale option"? What is a "scaler"? Perhaps this is standard terminology in some other application that I haven't encountered.

A picture tells a thousand words. I suggest uploading a sample file.

Hi Paddy - thanks for the message.  Apologies if I have confused... I'm new to Inkscape and thought some of this may be known terminology.  Here's an actual example...

1.  I draw a line using the Bezier curve tool (keyboard shortcut B).  I then select line Nodes (Keyboard N) and change the nodes to 'Symentric' using button option in header toolbar and create the curved line I need.  The line is drawn in an Ellipse shape.  Because the line is pretty thin, I then use the "Scale" option in the toolbar to increase the width - see first attached screengrab (Screenshot_2023-07-10_213144.png).  Everything is fine until now.

But now I copy and paste the same line into a brand new file and the line is back to being narrow - see second screengrab (Screenshot_2023-07-10_213041.png).  The "Scale" amount remains unchanged, but the line is thinner.  This means I need to resize the Scaler by trial and error to get back to the same width (even more frustratingly, when I click on the line in the first file, the Scale of each line doesn't show in the header bar, so there's no way for me to know what original scale each line was). Note both screengrabs are the at the same 300% zoom.

How do I ensure the width of the line doesn't change when I copy/paste a line to a new doc?

I've even noticed that sometime I will open a perfectly setup file, and even if I nudge an unrelated line, other lines widths will jump thinner or thicker..

Any ideas why this is happening?

Or is there a more reliable way of controlling the width of the line in the first place?

Hope this makes more sense now

Thanks

Now I understand, and yes, that is definitely frustrating. I can't reproduce this behaviour on my system but I've had similar problems, mainly with the Offset live path effect.

Stretching an ellipse over bezier curve applies the [Pattern Along Path] path effect. You can see this in the path effects dialog [Path > Path Effects]. Each time you change your drawing, Inkscape recalculates all the path effects and updates the screen but on (thankfully) rare occasions the rendering engine messes up. In my case offset distances jump unpredictably on the screen from positive to negative even though the path effect parameters are unchanged.

When this happens I must edit the shape to restore the initial correct appearance. The only sure fix is [Path > Object to Path] which of course removes the responsive behaviour of your effects, but you should do this anyway for every drawing before sending it out for print.

I haven't filed a bug report because I can't reproduce this reliably. If you can demonstrate this consistently, you might consider posting one yourself. 
https://inkscape.org/forums/beyond/think-you-have-a-bug/

Thanks Paddy... I think you've found it for me!... Path > Path Effects > Width.  This setting seems to increase/decrease the line width without using the "Scale" function, and seems to be more stable in my quick testing.  I'll do a bit more and see if it behaves.  Now I just have >150 files to update :(.... but still, good you have highlighted

I never thought about needing to 'object to path' all the lines too; I was goimng to do that with the text, but thought that the line items I could leave.  I'll do as you say re those before sending to the printers

Thanks vm!