Windows 10: Can't trim video Windows 10

I just recorded a video using OBS on my Acer Aspire 5 laptop and when I went to trim about 10 minutes off of it it says that I don't have permission to save changes to the file and that I should try saving a copy, This hasn't happened before and I am confused, can someone help?

:)

 

Edit Video in Photos- Trim

Hi,

You can trim the beginning and end of a video so your movie shows only the part of the video you want.
To help us determine the appropriate troubleshooting steps that can resolve your concern, we would like to ask the following questions:

• What is the build and version of Windows that you’re using? To check, type
  winver in the Search box, select the resulting command and send us a screenshot of the information window.
• What is the name of the application used when capturing videos?
• Is it happening to all the videos that you captured?
• What video player are you using to watch this video file?

We look forward to your response.

 

Trimming Videos in Windows 10

Why are videos disproportionately smaller after trimming in Windows 10? For instance, if I trim 5 seconds (25%) off of a 20 second video the size in megabytes is reduced by (lets say) 80%.

Note: There is topic that fits this question

 

trim video

How do I trim sections from a video in Windows 10? If it's to be trimmed in Photos, I'm unclear how to properly position the bottom brown line (left and right sides) and white circle....and whether/how I need to save sections to the storyboard...and
then how to save all sections of storyboard into 1 video. Very frustrating trying to find clear-cut instructions.