tToday was a boring day. Today was a boring day.

tToday was a boring day. Today was a boring day.

Proper capitalisation should be observed, at least when not writing in highly casual situations such as texting.

ıI stayed in front of my computer all day. I stayed in front of my computer all day.

ıI stayed in front of my computer all day. I stayed in front of my computer all day.

ıI watched a movie,youtube and / some movies, youtube videos and a series / some series. I watched a movie / some movies, youtube videos and a series / some series.

ıI watched movie,ys, YoutTube and TV series. I watched movies, YouTube and TV series.

(1) "YouTube" is the name of a company/service, and is a proper noun. It should be properly capitalised. (2) "Series" might be a little vague. What kind of series are you referring to? TV series? Drama series? Film series? Whatever it is, I'd suggest clarifying it in your writing.

ıI think ıI am depressed. I think I am depressed.

ıI think ıI am depressed. I think I am depressed.

tToday? Today?

tToday? Today?