I cant edit my company details on my invoices. Please help.

We're glad to have you here in the Community, @imran_one.

Let's go to the Custom form styles and make some modifications to your invoice template. From there, you can edit your company details.

Before we proceed, may I know where you're trying to edit your company details? And did you get an error message when modifying it? Any additional information would be greatly appreciated.

Here's how:

1. Click the Gear icon, then select Custom form styles.
2. Select the invoice template you're using, then click Edit under the Action column.
3. Go to the Content tab and select the Header part of the template.
4. In the fields, edit your company details so it'll reflect on your invoices.
5. Click Done once finished.

I've got you this article for more details: Customise invoices, estimates, and sales receipts in QuickBooks Online.

Just in case you want to import custom form styles, feel free to check out this article for the detailed steps and information: Import custom form styles for invoices or estimates.

Please keep in touch if there's anything else I can do to help you succeed with QuickBooks. I've got your back. Have a great day.