how can i change the text of a button in a plugin

You’ll need to talk to the plugin author about that, as we don’t support commercial plugins here and hacking the core plugin is a very bad idea.

Changing text in any plugin is easiest with Loco Translate. Just create an English template (if you don’t change the language) and edit the words you want to edit.
This of course works only with plugins that are localization-ready.

thank u @prasunsen but i want to change the code ?

I’d second Andrew Nevins that hacking the code directly is a bad idea, but if you want to do it, it’s up to you.

Or to put it like this. You change the code directly, the plugin gets updated and you’re back to square one. ??

This might help you out. Have a look:

.watupro_buttons td input {
// Your CSS here
}

The “toggle answer feedback” button:

.watupro-main-feedback input[type=button] {
// Your CSS here
}