Glyphs

As per shattered pd wiki, "boosting a glyph further increases effect of the wearer"

My questions

1. Boosting a glyph means upgrading the armor?
2. If I apply a glyph on a armor +6 then its effect will be automatically boosted by the level of armor?
3. Lastly, if I apply a glyph on low tier armors like leather or cloth then the chances of the effects of glyphs are better with subsequent upgrades than a plate armor?

Thanks