settle down/settle in
Hi,

When looking up "settle down/settle in" in dictionaries, I find that the two phrases both share the same meaning of "making oneself feels comfortable in a place". So I wonder whether I could use "settle down/settle in" interchangeably in this meaning?

Here are two examples extracted from Macmillan:

1. We found our seats and settled in for the journey. - Can I use "settle down" here?
2. I settled down in front of the television for the evening. - Can I use "settle in" here?

Thank you very much for your help!

Question

settle down/settle in
Hi,

When looking up "settle down/settle in" in dictionaries, I find that the two phrases both share the same meaning of "making oneself feels comfortable in a place". So I wonder whether I could use "settle down/settle in" interchangeably in this meaning?

Here are two examples extracted from Macmillan:

1. We found our seats and settled in for the journey. -> Can I use "settle down" here?
2. I settled down in front of the television for the evening. -> Can I use "settle in" here?

Thank you very much for your help!

Answer

Both aren't technically wrong, but they just sound a little strange switched. 
"Settle down" can mean what the commenter above me mentioned, but also there's a term that some people use: "They/He/She settled down" which basically means somebody got married or maybe moved to one place and lived there for awhile, while "settling in" can mean someone that is finally adjusting to a new life after moving to somewhere new. 
Just a few more meanings of those terms and a little more about how they differ, I hope this helped!

Answer

I think "settle in" would sound a little strange in the second sentence, but not necessarily "wrong".

"Settle down" is also a way to tell people to calm down. If someone is getting really angry and starts shouting, you could tell him to "settle down". You cannot use "settle in" this way, so they aren't always interchangeable.