Can anyone patiently explain how the online system works ?

im confused

1.what is the difference between the 2 apps - Immoservice and Section 38 ?

2. i am a house owner - do i use Section 38 app to notify residents who stay in my home ? is this equals as "registering address" ? do i need to do this for myself too ?

3. this is the 3rd time i tried to do a 90 days report online for myself and got rejected, they always say my address doesnt match with the one in the system, i dont know why

i used this website to do it -

[members only]

should i be using the immoservice app for that ?

TIA