1. The sale of jeans stopped growing because the worldwide economic situation got worse.
Explanation:

"Worldwide" (toàn cầu) is the correct form of the word "world" to describe the global economic situation.

2. All passengers must complete a visa form upon arrival at the airport.
Explanation:

"Arrival" is the noun form of "arrive," used here to indicate the act of reaching the airport.

3. They had to walk about 500m from the parking lot to the entrance.
Explanation:

"Entrance" is the noun form of "enter," referring to the point where they entered the building.

4. The bus left the highway and turned into a smaller western road.
Explanation:

"Western" is the adjective form of "west," describing the smaller road in a particular direction.

5. They are listening to the public announcement.
Explanation:

"Announcement" is the noun form of "announce," referring to the information being shared publicly.

6. People can use the telephone to communicate with friends by means of short message communication or chatting.
Explanation:

"Communication" is the noun form of "communicate," referring to the act of exchanging messages or chatting.