Hello, @MROCA2018.
Allow me to share with you some information about why you're seeing the negative expense amount in your Profit and Loss after importing.
The negative value appearing in the expense section means that there are Expense transactions (or perhaps Journal Entries) which were credited for an expense account or debited it for a negative value. I'll walk you through on how to check this:
- Go to the Reports tab.
- Click on the Profit and Loss report in the Business Overview section.
- On the line with the negative amount, choose the number to open a Transaction Report having the items with that amount.
- Click on the report to open and review any transaction.
I'm adding a brief video to display the process:

Learn more on how to import files in QuickBooks Online by checking out these articles:
Get back here in the Community if you've got more questions about importing your files in QuickBooks Online. I'll be around to help. Have a great day and take care always!