Change Video File to change clips on track?

[Zezin]

So I was making a compilation of videos by grabbing bits and pieces of each video. 

I did not realize until I exported that a lot of my video files have different dimensions  and when put into the compilation it looks really bad. But the idea of going to each and every clip and widening them do NOT appeal to me for obvious reasons.
Is there any way to just change the video file that I got the clips from and have that affect all the clips on the track?

[borate]

On the sequence clips can be selected (highlighted), then the fx button for any one of them clicked.

When the effects box appears click the large green + sign and scroll to the Aspect Ratio Transforms section.  Choose one of the three options.  Then click the chevron to the right of the Auto Aspect Ratio field for a drop-down box of choices.

Lastly, click the fourth icon from the left in the toolbar (REPLACE clip chain) to add this change to all selected clips.   The fifth button on the toolbar will APPEND to existing effects.

The aspect of Individual bin clips can also be changed prior to dropping them onto the sequence.  Use the right-click menu.

During export click the RESOLUTION box to affect the overall output.  The CROP AND ZOOM button may prove useful.

A little experimentation should achieve the desired result.