As I have already told you, your tax preparer is wrong. Read this: https://www.irs.gov/publications/p929
A dependent whose gross income is only earned income must file a return if the gross income is more than the amount listed in the following table.
A dependent whose gross income is only unearned income must file a return if the gross income is more than the amount listed in the following table.
A parent of a child under age 19 (or under age 24 if a full-time student) may be able to elect to include the child's interest and dividend income on the parent's return.
Now read this: https://blog.taxact.com/tax-mistakes-parents-make-that-end-up-costing-them/
Highlight from "3 Tax Mistakes Parents Make That End Up Costing Them"
Never report your child’s wage income on your return.
It may seem like the easy way to deal with a small W-2 form, however children must report earned income on their own return if they are required to file.
And again: if a child files his or her own tax return, that does not necessarily mean that the child cannot be claimed as a tax dependent on the parents' tax return.
Fire your current tax preparer. He or she is dangerously clueless. Either that, or you are completely misunderstanding what your tax preparer is telling you.