I knewfound out about it for the first time when I was watching a YouTube video. I found out about it for the first time when I was watching a YouTube video.

I knew it for the first time when I was watching a YouTube video. I knew it for the first time when I was watching a YouTube video.

I'd say "I found it for the first time" or "I learned of it"

I knewheard about it for the first time when I was watching a YouTube video. I heard about it for the first time when I was watching a YouTube video.

In the video, one of the foreign personalitiesople said that “One of my first triggers to becoming interestinged in Japan iwas the theme song of “Hi Hi Puffy AmiYumi”.” When she was a child, she liked the part of the lyrics that said “Anything is possible.” For me, Puffy was a just singing group. In the video, one of the foreign people said “One of my first triggers to becoming interested in Japan was the theme song of “Hi Hi Puffy AmiYumi”. When she was a child, she liked the part of the lyrics that said “Anything is possible.” For me, Puffy was a just singing group.

In the video, one of the foreign personalities said that “One of mythe first things to trigger tomy interesting in Japan iwas the theme song of “Hi Hi Puffy AmiYumi” theme song.” When she was a child, she liked the part of the lyrics that said “Anything is possible.” For me, Puffy was a just singing group. In the video, one of the foreign personalities said that “One of the first things to trigger my interest in Japan was the Hi Hi Puffy AmiYumi theme song.” When she was a child, she liked the part of the lyrics that said “Anything is possible.” For me, Puffy was a just singing group.

"that said" could also be "that went," or you could say "she liked the lyric "anything is possible."

In the video, one of the foreign personalities said that “One of mythe first things that trigger toed my interesting in Japan iwas the theme song of “'Hi Hi Puffy AmiYumi”.” .'” When she was a child, she liked the part of the lyrics that said, “Anything is possible.” For me, Puffy was a just singing group. In the video, one of the foreign personalities said that “One of the first things that triggered my interest in Japan was the theme song of 'Hi Hi Puffy AmiYumi.'” When she was a child, she liked the part of the lyrics that said, “Anything is possible.” For me, Puffy was a just singing group.

I actually really don't know where that period is supposed to go. Usually, if the quotation is at the end of a sentence, then the period goes inside the quotation, even if it wasn't part of the quote, but your sentence ends with two quotations so... But anyways, quotes within quotes are marked with ' instead.

In the video, one of the foreign personalitieer youtubers said that “One of mythe first trigger tohings that had grabbed my interesting in of Japan iwas the theme song of “Hi Hi Puffy AmiYumi”.” When she was a child, she liked the part of the lyrics “Anything is possible.” For me, Puffy was a just singing group. In the video, one of the foreigner youtubers said that “One of the first things that had grabbed my interest of Japan was the theme song of “Hi Hi Puffy AmiYumi”.” When she was a child, she liked the part of the lyrics “Anything is possible.” For me, Puffy was a just singing group.

So I was surprised they became cartoon characters in the US. So I was surprised they became cartoon characters in the US.

So I was surprised that they became cartoon characters in the US. So I was surprised that they became cartoon characters in the US.

So I was surprised they became cartoon characters in US. So I was surprised they became cartoon characters in US.

"was," or "am" if this is present tense

So I surprised ithey became a cartoon characters inin the US. So I surprised it became a cartoon in the US.