If we activate the discount but it we cant exchange it to be applied after tax because we dnt have the arrow icon next to the discount field. ?

Let's perform some troubleshooting steps so you'll be able to see the drop-down arrow next to your discount, usermaysa_anati.

This happens if your browser is full of frequently accessed page resources that may cause some unusual responses. You can log into your QuickBooks Online (QBO) account in a private window (incognito). Here's how:

• Press Ctrl + Shift + N (Google Chrome).
• Ctrl + Shift + P (Firefox).
• Control + Option + P (Safari).

Once you're already signed in, you can access the discount field to check if the drop-down arrow is already showing. If so, you can clear the cache to speed up the loading process.

Every so often the cache becomes overwhelmed with older data which can potentially cause viewing and performance issues. Clearing it will refresh the system, and you'll be able to work with a clean slate. You'll also want to try using other supported browsers. 

Please check this article if you need information on adding a discount: Add a discount to an invoice or sales receipt in QuickBooks Online.

Also, QuickBooks Online has different kinds of reports that will show the information you need. You'll can visit this article for your reference: Run reports in QuickBooks Online.

Please let me know if you have any other concerns with your discount. The Community always makes sure to get you covered.