Select the tab whose label you want to change, and select "Tab setting" in the setting section on the left.(Figure 1)
Enter a new label and press the "Update" button.
The label is changed.(Figure 3)
You can change the position of the tab with drag & drop.(FIG. 4, FIG. 5)
After choosing an arbitrary tab, press the "Cancel" button once.(FIG. 6)
Then you can press "Add" button.(FIG. 7)
Enter the name of the newly added tab and press the "Add" button.(FIG. 8)
A new tab is prepared.(Figure 9)
Add a menu icon in the tab.