Why does Env explode text in a pdf?

 Import pdf to worksheet. Do NOT convert to image.
I wish to underline a phrase to highlight something. Or maybe I just want a word italicized or emboldened. Doesn’t seem to matter.
Edit the pdf indicates that every character is a separate text entity!
Why?
So I double-click the first character. In the editor I just mark it as underlined then click OK. Text height has increased significantly!
Why?
Double-click another character, then just click OK. Text height again increased significantly!
Why?
Check out the top right-hand corner

PS

will this fix the glitch where a thread that ended in February displays before one in which the last comment was on April Fools Day?