Click on the hamburger menu and you will see the second last option of the menu, which is Settings.

Go with the Settings and you will find Job option on the settings list.

Select the Job and you will see the Job settings on your screen.

Click on the Job Type/Services.

Now Job Type/Services Settings screen will open with Job Type/Services list and the Edit icon under the Action column.

Select the edit icon of the same row of Job Type/Services you want to edit.

Clicking on Edit icon will open up a pop up having two fields.

Edit the Type/Services field, It is mandatory. And the service cost field.

After editing both the fields, click on the Update button.