Hi, I am trying to install Google Tag Manager on my website. I have been making changes to my child theme through the CSS editor. But now that when I tried to paste the codes from GTM to "Appearance -> Editor -> header.php" at dashboard, seems all customizations appear only at the soledad theme instead of the children theme. For example the header.php is at the parent theme. For the child theme, I can only see only two almost empty files "style.css" and "functions.php". Does it mean now that all customizations all made at the parent theme instead? Which step did I do wrongly?

Many thanks.