Here are three ways to apply a global effect...
1. Select all clips (ctrl-A). Right-click on one of them. Program the ZOOM. then click the effect chain button on the toolbar... .
The effect will be applied to all selected clips.
2. Simply export the project, re-import the result, apply the effect and export again.
3. Create a new, blank sequence by clicking the + sign to the right of sequence 1... 
Then, above the bin, top-left, click the Sequences tab... 
Right-click on sequence 1 and... 
Your project is pasted as a SINGLE clip. Now apply the ZOOM (or other effect). Export Sequence 2.
Whatever changes you make, Save Project File AS routinely, giving it a unique # or name, so as not to overwrite prior saves. Using Save Project Files (no AS) will overwrite. From the HOME tab, that choice is available by clicking the chevron to the right of the Save Project button on the toolbar. Then you're protected and can revert if need be.