The Internet is NOT working for me today, only making me more confused.

What’s the deal with international carry ons? I keep seeing conflicting information. I own this suitcase and I always carry on. I am flying United and I can find a policy on carry ons in general, should I assume this applies to international travel? The last few times I’ve flown internationally I’ve checked so I am in the dark.

I am only concerned because I booked my flight to and from LAX (where I am flying to LHR from) separately from my England flight, so I am worried about checking my bags as they won’t be automatically transferred to my next flight...