Here you go, some suggestions, if I may.
A) An exercise from Cambridge.
B) You used the right word “weather” then next, you made a typo with “wheather” not wheater (dourado/mel) and not weather (atmospheric conditions/season).
C) my humour is pretty much the same most of the time.
D)...so if my mood changed with every single climate change, that would drive me crazy.
E)...in general I am very skeptical when some people say that the weather causes a huge influence over some peoples traits (or their mood).
F)...For example, [space here – after the commas] I am Brazilian...
G)...uncommon (maybe “unusual” would be a better word here.)
H)...some foreign people say that Brazilians and Latinos (curiously you used capital B now, but forgot that “Latinos” is a word known in America, Latin
I am afraid is not the proper word here)https://www.youtube.com/watch?v=BgB3cm8Pws4
J)...makes its people be more cold and not much friendly. (nothing wrong with “be more cold...” but could be dropped, then “….makes its people more cold…” would make the same effect.
K) Well,I have to say that I know many europeans,northamericans and japaneses that have shown me the opposite of these stereotypes.
Here your opinion gets a bit much personal, a workaround to say the same would be:
“From my experience I know many Europeans, Americans, and Japanese people that are the opposite of such stereotypes.”
L) On the whole,I think (again the comma-space advice here).
By and large, your piece of text (or interview draft, I don´t know) shows your knowledge, that you master English and can express yourself. Only some minor corrections that if I had not read it with a magnifying glass I couldn´t spot. So, congrats on your skills.
I didn´t exhaust all possibilities, others may polish it further. So, this is a kick-off.