Angular-6 based on the select inputbox and select dropdown not showing properly

This question is maybe asked, but that is not solving my issue.

The drop-down of key contains database, desktop and account. Based on the drop-down of key the value drop-down and inputbox will be changed.

https://stackblitz.com/edit/angular-ivy-zahevb?file=src%2Fapp%2Fapp.component.html

My issue: When I click 1st row it seems good. But when I move on to 2nd row the data append not properly. And when I select account previuos row drop-down also changed as inputbox

Eg:

1. In 1st row I select Database,value should append ['mysql', 'oracle', 'mongo'] in drop-down
2. In 2nd row I select Desktop, value should append ['dell', 'lenovo', 'hp']
3. In 3rd row I select Account the inputbox will show

app.component.ts

import { Component, VERSION } from '@angular/core';

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: [ './app.component.css' ]
})
export class AppComponent  {
  dynamicArray: Array<any> = [];
  newDynamic: any = {};
  dbValue = ["mysql", "oracle", "mongo"];
  desktopValue = [{'id':'1', 'name':'dell'}, {'id':'2', 'name':'lenovo'}, {'id':'3', 'name':'hp'}];
  isdbShow:boolean = false;
  isdesktopShow:boolean = false;
  isaccountShow:boolean = false;
  ngOnInit(): void {
    this.newDynamic = { title1: "", title2: "", dropdownDataDb: [], dropdownDataDesktop: [] };
    this.dynamicArray.push(this.newDynamic);
  }
  addRow(index) {
    this.newDynamic = { title1: "", title2: "", dropdownDataDb: [], dropdownDataDesktop: [] };
    this.dynamicArray.push(this.newDynamic);
    console.log(this.dynamicArray);
    return true;
  }

  deleteRow(index) {
    if (this.dynamicArray.length == 1) {
      return false;
    } else {
      this.dynamicArray.splice(index, 1);
      return true;
    }
  }

  changed(value, index) {
    let dropdownDataDb;
    let dropdownDataDesktop;
    if (value == 1) {
      this.isdbShow = true;
      this.isdesktopShow = false;
      this.isaccountShow = false;
      this.dynamicArray[index].dropdownDataDb = this.dbValue;
    }

    if (value == 2) {
      this.isdbShow = false;
      this.isdesktopShow = true;
      this.isaccountShow = false;
      this.dynamicArray[index].dropdownDataDesktop = this.desktopValue;
    }

    if (value == 3) {
      this.isdbShow = false;
      this.isdesktopShow = false;
      this.isaccountShow = true;
    }
  }
}

app.componet.html

<div class="container" style="margin-top: 5%">
    <table class="table table-striped table-bordered">
        <thead>
            <tr>
                <th>Action</th>
                <th>key</th>
                <th>value</th>
            </tr>
        </thead>
        <tbody>
            <tr *ngFor="let dynamic of dynamicArray; let i = index;">
                <td (click)="deleteRow(i)">
                    <i class="fa fa-trash fa-2x"></i>
                </td>
                <td>
                    <select [(ngModel)]="dynamicArray[i].title1" class="form-control" #sel (change)="changed(sel.value, i)">
            <option [value]='1'>Database</option>
            <option [value]='2'>Desktop</option>
            <option [value]='3'>Account</option>
          </select>

                </td>
                <td>
                    <!-- show db data -->
                    <select *ngIf="isdbShow" [(ngModel)]="dynamicArray[i].title2" class="form-control">
            <option *ngFor="let data of dynamicArray[i].dropdownDataDb;">{{data}}</option>
          </select>
                    <!-- show desktop data -->
                    <select *ngIf="isdesktopShow" [(ngModel)]="dynamicArray[i].title2" class="form-control">
            <option *ngFor="let data of dynamicArray[i].dropdownDataDesktop;">{{data?.name ? data?.name : data}}</option>
          </select>

          <!-- show account data -->
          <input *ngIf="isaccountShow" type="text" [(ngModel)]="dynamicArray[i].title2" class="form-control">
                </td>

            </tr>
            <tr>
                <td (click)="addRow(0)">
                    <i class="fa fa-plus fa-2x"></i>
                </td>
            </tr>
        </tbody>
    </table>
</div>