Hello umhlalityres!
We're unable to customise the icon bar in QuickBooks Online. If you have suggestions about it, feel free to share it with us, so I can relay it to our engineers. We've been doing changes in QuickBooks based feedback and suggestions. This
I just thought that you might need some references in the future. Feel free to check our Help articles for QuickBooks Online.
If you can think of any options that will make your work more efficient, feel free to share it with us in the Community.