Text placeholder on master layout not visible on slides

Hello JeroenVerhoeckx,

Happy to help!

Yes, you are correct. When you make a change to a Slide Master layout, you'll need to apply the layout to all slides that use it to see the changes take effect. I understand that doing this to a project that has a high volume of slides can be tedious, but one way to speed up the process is to apply the layout to multiple slides at once. Here's a recording I made that shows how you can update the layout of multiple slides in one go.

Hope this helps!