sounds like your title needs to be changed.
also sounds like you need to confirm what your role is with the boss.
The more that gets dropped on your desk, and you handle it and "they" know you will handle it, the more it will happen.
For us,
* Sales does all aspects of the client, setting up their account, collecting/processing payments, Their commission happens AFTER payment in full
* Design does the proofs AFTER deposit (unless approved for NET terms), makes edits as needed, creates the "permit" designs, preps files for production (all forms of production).
* Production preflights the files, preps for production, orders material, QC the finished good against the approved proofs
* Office Manager oversees all and handles calls. also assists whoever is bottlenecked.
granted this is the PERFECT world example, and there is cross-over (when needed) in the real world.