Make canvas of a letter bigger?

I making a font that consists of icons. When I use the finished font, the space character isn’t wide enough, so it is difficult to tell where one word (made of icons) starts and the other ends.

I opened up the space character in Glyphs, but I am not sure how to make the canvas wider, so the space becomes wider.

Screen Shot 2021-02-05 at 18.00.01

How can I make my space wider? Thanks!

You need to select the field —200— and type the value of space that you need.