These days, I feel insecure about my future.
After graduation from university, I was looking for a chance to work abroad, especially in airline companies based in foreign countries.
After a long (lasting) preparation for job interviews, I was finally done with my first interview at Qatar airways’.
However, I now fear that I won’t get the chance to qualify for a final interview,
because I felt too nervous at that time. So I think I should have replied to their questions in a different way.
In addition, It seemed that the interviewer wasn’t interested in me at all.
The reason I say that is because she only asked 3 simple questions with a totally indifferent attitude.
The reason why I felt that way is she asked many questions to other applicants, and she looked much more interested in comparison to my case.
So after this first interview, I was quite depressed because of her.
The thing staff are requested the most when working in this airline company is positive attitude.
In this respect, I think I am not as positive as they require.
Does anyone know how to be a positive person in life?
I know it is a quite difficult thing to have.
But I am really wanting to change my personality and attitude toward my life.
I hope I will grow up in a better way through these experiences.
Bye!

Sorry this is my first correction on Italki, I tried to use an app that shows which corrections have been made, but when I pasted it, the corrections had disappeared... If you want I can send a screen capture to you, I'm just not sure we can do it on the website.

There were a few phrases that needed to be modified to sound more English, but overall there is one advice that came to mind when correcting it: I have always been advised not to start sentences with words like "but", "because", "or", "and", "so"... Not sure what others will think though, as it all depends on how formal you want to sound. "so" might be the most acceptable, as it is a common filler in English. You can easily manage this by changing those words by more "formal-sounding" ones, for example:

But > However,
And > In addition,  
Or > Alternatively, / Otherwise
Because > This is why... / For that reason... (+ many variations)
So > Therefore, / Consequently

Hope this helped, 

Take care 

These days, I feel insecure about my future.

After graduating from university, I have been looking chance to work abroad, especially in one of the airline companies based in foreign countries.
After long preparation for my first job interview, I had my first part of the recruitment process with Qatar Airlines, but I am not confident that I will get a chance for a final interview.
I felt so nervous at the time, so I think I might have replied to their questions in the wrong way.
In addition, it seemed that the interviewer didn't have any interest in me at all, because she only asked three simple questions and had a totally indifferent attitude to my answers. 
The reason why I felt like that is because she asked many other questions to the other applicants with real interest, unlike me.
So after having the first interview, I was quite depressed because of her.
The most required thing for airline (crew/staff) to have is a positive attitude, but in that respect, I think I am not as much of a positive person as they require.
Does anyone know how you can be a positive person in life?
I know it is quite difficult thing to have, but I really want to change my personality and attitude towards my life.
I hope I can learn from these experiences and be the person I want to be. 

Bye!

Firstly, if this is true and it seems it is, don't wory! You are fantastic, I'm sure. Perhaps the interviewer was in a mood, perhaps you misunderstood her. If it doesn't work out, keep trying, be positive! If the job doesn't fit perhaps you just need to try and find a different one. 

A few things:

If you are using a but or a because, use a comma to break-up the sentence if you feel the need.

Never start a sentence with a lowercase letter. 

Numbers smaller than 10 should aways be written e.g. three not 3. 

We use 'have been', so present perfect continuous if the action started in the past and is still going on, as in you are still looking for a job in an airline when you wrote this. 

When talking about 'life' as in the life that is about to happen to you, use, "this life is fantastic" or "In the future, I want my life to be awesome", or "your life is brilliant, I wish I could have a life like yours", or "They're life is perfect!". We don't often say 'the life' unless you are refeering back to something you've said before such as "the life I used to live was boring, then I got a new job and now life is awesome!"

You write very well, good luck finding the right job!