How to import an XRP Ledger account in Read Only mode
You can import an XRP Ledger account in either of these two modes: Full access - Choose this option if you would like to be able to interact with your XRPL account. ie. if you would like to create a Trust Line or send XRP to another account.
Read only access - Choose this option if you would like to simply follow the activity of an XRPL account. This option does not allow you to sign transactions on your account.
Most people choose to import their accounts with Full access but if you are interested in just monitoring an account's activity, you can import in Read only mode.
1) Launch Xumm then press the Settings button, choose Accounts then press the + Add account button.
You should see this screen:
Press the Import an existing account button.
Select Read only then press Next.
Enter the r-address of the account you would like to import then press Next.
Enter the label of the account then press Next.