I finally saw why my home printer and the shop printer give totally different reds
So I made a birthday banner for my kid's party on my laptop and printed it at home, and the red looked fine. Then I sent the same file to the print shop over on 5th Street for a bigger version, and that red came back looking like old brick. The guy there said my home printer auto switches to CMYK while my screen stays RGB, and my file had no color profile locked in, which is why the shop's machine guessed wrong. I get the basic idea now but I don't know how to set this up so it looks the same everywhere. What's the actual fix here, do I need to save it a certain way before sending it out?