a lot of fans.

Audiences are a lot of people, so you should use were.

It should be ''went to the studio'' not ''want to studio''.

You forgot comma after ''In the future,...''.

BTS group is singular, so you should use ''has''.

''She is the top ten outstanding students in my class'' sounds a lot better.

In the evening, I will go to the concert at 5:00 pm. Use future form to talk about your future plan.

..........., who produced a lot of number 1 songs.

Audiences are plurals, so you should use verb to be ''are''.

4. ''Thousand of fans''

5. ''I have to wait in line very early to get into in front stage''

We don't ask ''Have you ever gone to...'', we ask ''Have you ever been to (somewhere)'' to ask for the experience.

''There are a lot of musicians in Cambodia'' sound a lot better.

''live Tv show''

''audiences''.

''She is the most not a most''

If you never get the chance to go anywhere yet, we always use present perfect tense like', ''I haven't been to (somewhere) instead of saying ''I haven't gone''.

2018 is in the past, so it should be ''Kmeng Khmer group was'...''