Hi! I want to change a variable inside of pulumi.all.apply method ... but when I these method end, values become to original values .... how could this value be maintained?

.Apply(..)

transforms your output so you need to then use your new output going forward.

// receive old output
var oldOutput = ...;

// transform
var newOutput = oldOutput.Apply(...);

// use newOutput

does that help?

I need to save value ouput into string variable.

The output value is asynchronous so it isn't known at compile time, you need to either transform it and continue to pass it around / manipulate it as

Output<T>

or you need to await it so that you can manipulate it synchronously