Here, I think I see something in your explanation;

"I copy the Word text, and paste, to the Reply to Thread window or New Post window.

I then highlight the text to be linked to, click the Link Icon, open the original post or video and copy the address from the address bar, and paste to the Hyper link window. Click preview to make sure it opens to the correct link and upload the post."

When you highlight a group of words/text, then dump a hyperlink into it, you have loaded a hyperlink address onto that same sentence/line. Depending on how long the hyperlink address is & the rest of your sentence on that same line, will decide if the text box gets "widened" & distorted.

look at the front page of SRP, there are tow hyperlinks, one in the Hones & steel article & the other in the restoring the past article.
The hyperlinks are on a line of their own, no problems this way.

I'm going to bring post # 11 here in this thread & play with it, lets see if I can get the result you did.