So you dont change "o" to "a" when describing the colors of objects to match the object? Ie; sofá amarela
You do, but sofá is masculine, so it is "sofá é amarelO". For example, if it was "the television is yellow" it would be a televisão é amarela because a televisão is feminine.
o sofa do nosco e amarelo, is this a possibility?
No. You can say "o nosso sofá" or "o sofá nosso".
Is one more natural-sounding than the other? Noun/adjective placing is still confusing me, and Duo rejected "o sofa nosso" here.
O nosso sofá is the natural way to say it. =)
"Nossa poltrona é amarela" why is this not correct???
Poltrona = armchair
Poltrona=airplane seats, that looks like a "sofa" to me, don´t you think so?
Yes, poltronas can also be airplane seats, but also armchairs =) at least in Brazil...
When to use 'nos' , when to use 'nosso' :-/
Nós = we. Nossos(s), nossa(s) = our. Nos = us, ourselves, in/on/at the.
I am brazilian and I can answer some questions...