Big gaps between lines

Hi I have problem with my editor, I would like to know how to remove the big gaps between the lines. This happen when I copy paste from somewhere else. 

For example below is the text that I copy from somewhere else:

Hi,
My Isssue.
Thanks,
​Yasmin

After save, the gaps become something like this:

Hi,



My Isssue.



Thanks,



Yasmin

Anyone know how to solve this issue?Please share ur knowledge.