How to change caption style of Impress Insert > Media > Photo Album?

Much like this question How to insert many pictures into a frame on each Impress slide via Insert > Media > Photo Album by @LDP , I’m using Impress Insert > Media > Photo Album to create a slide show. I started with the Portfolio template and in the Create Photo Album wizard/dialog I choose “Add caption to each slide”.

I can’t seem to change the style of these captions all at once, and I have dozens to fix. I want them all to be Droid Sans, not Liberation Sans, and I want to change the caption background. But there doesn’t seem to be a “Caption” style anywhere!

  • If I click a slide in Normal view, “Title” highlights in the Styles and Formatting sidebar, but changing that style’s Character Font has no effect.
  • There are a bunch of odd Drawing styles in the Styles and Formatting sidebar, e.g. Text > A0 > Title A0, but I’ve tried changing these and it has no effect.
  • There doesn’t seem to be any style for this caption in any of the slide masters.
  • Fine, I’ll give up on styles and try to brute force. If I select all slides in normal view and change the font, it doesn’t affect captions. Change all text fonts in Libreoffice Impress presentation? (10 years old!) suggets switching to Outline view, Select All, and Format > Character… that doesn’t work!

The inserted photo album slides seem to use a new Master slide layout (Default 3 last time?), which I then switch to Title Only. What determines what Master Slide an inserted Photo Album uses? Can I create a master Slide for this and somehow add a caption to it?

It’s quite confusing and the Impress documentation doesn’t really cover this (and searching for it keeps giving me help with LibreOffice Writer). Many thanks for any explanation.

This is with LibreOffice flatpak on Fedora 34.

The captions on inserted Photo Album slides may be using the text style of the title text of the Default slide (not the Title Only Master slide that I set them to). Though I changed so many things in the presentation I probably got confused.

If I select the caption text and choose Format > Clear Direct Formatting, then I lose the white on black presentation of the caption and it reverts to black on white. So it seems there isn’t a style for these captions. Argggh.