When you open the master slide by View > Show Master Slides you need to click on the master slide in the navigator to make it active and to edit it. Perhaps you didn't. Another way to reveal the set of master slides is to pull down on the tab above and to the right of the first slide (see illustration)
With the Master Slide selected, add your text (text box) or logos somewhere on the slide - position your added text in an area that doesn't interfere with. Then hide the master slide (View > Hide Master Slides) and check that each of your normal slides now displays the text or logo you added to the master.
Not a problem.
Open your first master slide - the one with the added text.
Select the text and any graphic material you may have added > COPY
Reveal the next master slide in the set, click on it > PASTE
Repeat for each master slide. Save. Hide your master slides.
Now any slides you create using the masters (Title, Bullet with Picture, Blank, Phot Vertical, etc. will have your title on it.
Try it. This should fix your problem.