Communication between components Angular

I am new to Angular, I am trying to pass a value from one screen to another. The thing goes like this: On the first screen I select a "select" value (it's the id of a client), then I click on a button and it redirects me to another page where I need the client's id to be able to work. how can I do this? I have seen forms with input (but they are 2 different screens) and with observables (the id of my client is not saved) but they do not work for me, because I think it is necessary that the 2 screens are active at the same time.

I show you my service:

import { Injectable } from '@angular/core';

import { BehaviorSubject } from 'rxjs/BehaviorSubject';

@Injectable()

export class CommunicationService {

  private idCliente = new BehaviorSubject<number>(1232);

  cast = this.idCliente.asObservable();

  constructor() { }

   editidCliente(newCliente)

{this.idCliente.next(newCliente);

   }

}

On the first screen it changes the value and changes it correctly, but when I speak the second it always shows me the value with which I initialize in this case "1232".

So I'm using it on the first screen:

import { CommunicationService} from './communication.service';
@Component({
  selector: '...',
  templateUrl: "....",
  styles: [],
  providers : [...,CommunicationService],


})

export class RegistrarPropuestaComponent implements OnInit {

...
  public idCliente : any ; 
....
    constructor(... private communicationService : CommunicationService) { }



  ngOnInit() { 
    ....
    this.communicationService.cast.subscribe(cliente => this.idCliente=cliente)
...
  }
  changeidCliente(idCliente){  //esto se ejecuta en el change del select
    console.log("valor del idCliente despues del cambio en el select: " + idCliente);
    this.communicationService.editidCliente(idCliente);
  }

and so on my second screen, which is where I want to get the idClient value to be able to work.

import { CommunicationService} from './communication.service';
    @Component({
      selector: '...',
      templateUrl: "....",
      styles: [],
      providers : [...,CommunicationService],


    })

    export class RegistrarPropuestaComponent implements OnInit {

    ...
      public idCliente : any ; 
    ....
        constructor(... private communicationService : CommunicationService) { }



      ngOnInit() { 
        ....
        this.communicationService.cast.subscribe(cliente => this.idCliente=cliente)
    ...
      }

As you will see, it is almost identical.