Can't save multiple information in firebase

[Agent_Speaker]

Hii I'm getting information in database but it doesn't save when other user use my app then it changes . I want to save all details including the past one

[TIMAI2]

Looks like you and other users are overwriting the same tags?

[Agent_Speaker]

Yes , I don't know what to do with this

[TIMAI2]

Create a unique tag for each item, and then store the subtags under this tag:

sellItems
  item0001
    deviceBrandModel:"";
    deviceId:"";
    email:"";
    mobileNumber:"";
  item0002
    deviceBrandModel:"";
    deviceId:"";
    email:"";
    mobileNumber:"";
  item0003
    deviceBrandModel:"";
    deviceId:"";
    email:"";
    mobileNumber:"";
...

[Agent_Speaker]

What if , more than 3 users information collected, then it show on database or just change that past information?

[TIMAI2]

Firebase with a Web Component