I exported some charts from Excel as PDFs and imported them into Inkscape 0.92.3. I removed manual kerning from all the text. Now I'm trying to change the font size for the chart titles but for some reason only one of the selected text boxes is affected. How can I change all the boxes at once? Thanks.

I'd check to see what type of objects they all are.

Feel free to share the file for examination.... NVM, I see the link in the other thread.

TD

I'd guess they don't have the same styling there is some difference between in-line and t-span? That's what I remember from css.
What I mean is some text has the font style added to the text object attribute, and the others have an additional font described for just a selection of the characters -which happens to be all of them.

I'd look at the xml editor (Shift+Ctrl+X) when a text object with the desired result is selected, copy the style attributes,
then select the other texts and paste in&set the corrected attributes.

I'm not seeing the problem myself, provided you've got the text objects selected, not the groups they're in.

You could ungroup everything for simplicity, but if you want to retain the groups then the best option might be to use Object > Selection Sets, which will let you drill down into each group and add just the text objects to the selection set.

Whichever method you use, once you've got all the text objects selected (the status bar should show "X objects selected of type TEXT") switching to the text tool and changing the size from the toolbar should work (or at least it does for me).