Yes you can change this default.
1. Open a plot in which you want to change the default cursor.
2. Right click on the plot and select “Options”
3. In the Front/Back Options menu, go to the “Cursors” tab. Here, you can select the cursor type from a drop down menu (for example, Single X).
Then, you can change the default line style. In this case, I made it a thick red line.
When the cursor is as desired click “OK”.
4. To save this as part of your plot layout, open the plot menu, select “Save as Layout”. You can simply overwrite the existing FrontBack layout.
NOTE: if there are any curves in you display when the layout is saved, these curves will save as part of the layout. Make sure you delete the curves so the plot is blank (see picture above).
5. Now, when you add cursors, they will appear with the new line style.
NOTE: you will have to repeat this process for each cursor type in the menu that you want to change.
Let me know if this works,