Navigation bar dropdown items not editing

only the drop down menu title is being changed, but the items in the drop down are getting edited from frontend

Going to need a bit more detail than that in order to get a better handle on what the issue is.

It sounds like you can't edit the dropdowns submenu link texts.

Select the Dropdown component in the Overview pane in the bottom left of the app. Then just above the Live View pane above in the center, click on the toolbars Open button to expose the dropdowns submenu links. Double click on the text to edit the one you want to change. To change it's link, click on the Gear Icon in the Options pane on the top right of the app.