How to apply uniform layout to mixed slides in Impress?

Created a slide deck in Impress, some of the slides were copied from another presentation and pasted into the new file. The layouts are similar, but the fonts are different. Applying a layout from the pull-out menu on the right simply introduces additional text boxes.
I’ve checked the slide master and it is what I want on all the slides, but it’s font formats are not appearing on the old slides. What have I missed?
LibreOffice (the latest in the repositories for openSuse 42.1, 64-bit).

You haven’t missed anything I suppose.
In order to apply the “slide master changes” the slides should use the proper object. I mean if the title is the “title”, then changing the title in the slide master it will be reflected on each slide.
If the title (in your slide) is a text-box with some local formatting, I am afraid there’s not much you can do.
A good starting point to understand the structure of the content of your slide is the outline view.
From there you could also copy e paste content in the proper spot I hope.

Otherwise I am afraid it’s all manual :frowning:

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Futzing with the slides I found that when the headers are a mix of bold, italic, BI, and roman it is possible to make them uniform by changing the master slide font format back and forth. For example, if a mix of rom and ital, applying ital to the master makes them all ital. Unfortunately, beyond that it still seems to be manual (can’t change them all to rom).

I believe it’s because you’ve already specified the direct formatting on those old slides. Wonder if you can highlight those text boxes and click “Clear Direct Formatting” or Ctrl-M.