Does Illustrator's Scale Strokes & Effects preference apply per object or per document?

Direct Answer

Scale Strokes & Effects is a global application-level preference stored in each user's preferences file. It does not travel with the document, cannot be set per object, and there is no indicator in the file showing which state was active when the artwork was created.

Confirmed Behavior

• Location: Edit > Preferences > General (Windows) or Illustrator > Preferences > General (macOS).
• Scope: Applies to every object in every open document on that machine.
• Effect: When enabled, scaling an object proportionally scales stroke weights, live effect parameters (Roughen, Gaussian Blur, Drop Shadow, etc.), and pattern fills. When disabled, those values remain fixed in user space.
• Effect types: The toggle treats native Illustrator effects and Photoshop-based effects identically; there is no distinction.
• Document Raster Effects Settings: Control only the output resolution (ppi) of raster-based effects. They do not override or interact with the Scale Strokes & Effects toggle.

Why Output Becomes Unpredictable

Because the setting lives in the user profile, two team members opening the same file will see different results when they scale artwork if their preferences differ. The file itself stores no record of the author's preference state, and Illustrator provides no UI badge or metadata field to surface it.

Workarounds (No Native Lock-In)

1. Team convention: Document the required state (on or off) in your style guide and verify it during onboarding.
2. Pre-flight check: Before scaling critical artwork, open Preferences > General and confirm the toggle matches the project's agreed state.
3. Scripted enforcement: A startup script can force the preference to a known value, but this affects all documents for that user.
4. Non-destructive alternative: Apply strokes and effects via the Appearance panel, then use Object > Expand Appearance when the design is final. Expanded objects no longer respond to the toggle.

Verification Steps

1. Create an object with multiple fills, a stroke, and a live effect (e.g., Gaussian Blur).
2. Toggle Scale Strokes & Effects on, scale the object, note stroke/effect changes.
3. Undo, toggle the preference off, scale again, observe that stroke weight and effect radius stay constant.
4. Save, close Illustrator, reopen on a second machine with the opposite preference, and repeat the scale test to confirm behavior follows the local setting.

One Diagnostic Detail

If you need to preserve a specific scaled appearance across machines without relying on the preference, does your workflow allow expanding appearance (Object > Expand Appearance) at handoff, or must the artwork remain live for further editing?