Open a new document using whatever profile works best for you.
Create a path with the attributes you want.
Open the graphic styles panel. Drag the path you created to 'Default Graphic Style' while holding alt. This replaces the default graphic style.
Save the document to document profiles
C:\Users\Username\AppData\Roaming\Adobe\Adobe Illustrator 25 Settings\en_GB\x64\New Document Profiles
(on Windows)
Use that profile when creating new documents. It will appear under the tab it was created from (i.e. Print/Web etc.)
Or:
Open up all the documents in the New Document Profiles folder. Replace the default graphic style in each of them, then resave.