How do i change multiple descriptions?

iTunes 12.3.2.35

OS X El Capitan 10.11.3

Im having a problem changing multiple descriptions all at once. I'm talking about the descriptions, not the comments, and not the grouping. Heres what i do.

1. Highlight the multiple songs that i want to be changed all together.

2. Right-Click > Info

3. (And heres where I'm stuck.)

Note: Now i'm thinking that there is no way to do this. Except editing 849 items one-by-one. But now my question is: Has anyone every completed this before? I'd like to know how they did it; Change multiple descriptions all at once. Please, let me know. I'll be doing it the long way, while I wait for a response. Thanks.