iMovie one-photo slideshow with lyrics

I have iMovie 10.0.5 and I'm trying to create a one-photo slideshow with lyrics. I managed to extend that one picture -- as a background picture - the length of the song which is 6.3 minutes long.

The big problem is how do I insert the lyrics, as titles or captions, on top of the stretched background photo without the black background with white letters that are provided in Content Library/Titles.

I can do the Text titles directly into the picture used as background in a Windows program, but I can't stretch the background picture, and I want to keep everything in my Mac.

In summary, in iMovie I have a picture as the background the length of the song and I need to insert the lyrics as captions or titles whenever they change. But I don't want the black box where the titles are arranged: "lower third", "zoom", "soft edge" and so on. I just want a transparent, empty title so I can insert the lyrics, one sentence at a time.

Am I making any sense?

Thank you.