Please help us help you and fill where relevant:
Your LimeSurvey version: 6.3.6+231120
Own server or LimeSurvey hosting:Own server
Survey theme/template:Fruity/Sea Green
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Hello,
I want to add a show password bottom on admin login page.
I browsed some topics on the forum, But they are all for older versions.
I tried to follow the manual copy admin themes from /yourLimeSurveyDirectory/themes/admin to /yourLimeSurveyDirectory/upload/admintheme/ and add custom.js file to /yourLimeSurveyDirectory/upload/admintheme/yourTheme/scripts/ and add code to the custom.js file, But it doesn't work.
English isn’t my first language, so please excuse any mistakes.
Thanks in advance.

But it doesn't work.

This description doesn't help much. What happens? Where is the issue?

Did you set your new admin theme as the default?

This plugin : gitlab.com/SondagesPro/coreAndTools/select2ForAdmin

Add a script to all admin page

Think it work too in 6.X but no time to test
If 6X didn't deprecate beforeAdminMenuRender event …

Yes i set new admin theme as the default,but nothing changed on the login page.