Upload issues when posting to instagram

[Lewis5FDF]

I have 2 issues that i need help with. 

1) When i am editing in the software, the video takes up the full portion of the sequence. However then when i go to export the clip. The video isnt actually taking up the full screen. Image 1 & 2 shows what i mean. 

2) When i am editing in adobe the background i use is completely white. However when i export the videos to dropbox and then upload to instagram, the backgrouns have weird colour tints to them. Some coming up as grey, some as like hints of red & blue. 

any thoughts?