The following situations are possible:

You use your own legal guardian/training officer user account, and your students are at the same school?

In this case, your school must add the students to your associated master data element. Unfortunately, you cannot do this yourself. Please contact your school's WebUntis administrator.

You use your guardian/training officer user accounts, and your children are in different schools?

In this case, please create dedicated profiles under "Profile", allowing you to quickly switch between them. You will find detailed instructions here.

You share your student(s) user accounts?

In this case, please create dedicated profiles under "Profile" allowing you to quickly switch between them. You will find detailed instructions here.