You probably didn’t get an answer yet because that’s not enough information to explain what the problem is.
Do you mean you want to make a change to a theme’s template file(s)? If so, what specifically are you wanting to change? And on what website? Using which theme?
If you need to learn this from scratch, here’s a good introduction https://codex.wordpress.org/Stepping_Into_Templates
Sorry, maybe I wasn’t clear enough.
I meant I need to change de selected theme of multiple pages. I don’t need to change the theme itself, only change the selected one for another.
Let’s say, I have 100 pages using TEMPLATE B and 200 pages using TEMPLATE A.
What I need to do is to change the template of that 200pages, resulting in all my 300 pages using TEMPLATE B.
When in the Dashboard > Pages menu, tick the pages you want to change then use Bulk Actions > Edit. One of the options is to change the template.
But there’s probably a way to do this in phpMyAdmin that would be even quicker.
Wow! I’ve just discovered this. Thank you very much, it’ll work. I don’t mind spending 10 to 15 minutes in that, it’s fast enough.
Thank you very much.