EDIT: I posted too hastily. I just discovered that the solution to my problem is to bypass the regular Menus section and create a custom WIDGET, which can serve as a custom menus box. Below is my original post. I'll delete this post if you like.
I'm working with the theme twentyfifteen, which allows you to create two menus that are displayed in the sidebar.
I had no trouble creating the first menu, which is simply a list of links to the top pages on my site.
The second menu apparently has to be a "Social Links Menu" by default. For each new link you create, you're allowed to enter a URL and Navigation Label. For the Navigation Label, I entered the text that I assumed would display.
But when I preview my page, I don't see any text. Instead, I see a horizontal row of small, circular icons. Clicking on an icon takes me to the page I linked to, but visitors won't have a clue what they're clicking, since the icons all look the same.
Can anyone tell me how to convert the icons to conventional links?