there are quite some solutions

1-It could be that it is hidden behind another icon. Please try this: right-click on the empty space after the last tab and Customize.... With the mini window open you can move the other toolbars and icons around to check if the New Tab button is hidden. You can also check the Customize mini window for the icon named New Tab. Otherwise clicking Restore Default Set will hopefully restore it back. Please note that though nothing is uninstalled or disabled when you click Restore Default Set, you may have to redo all manual/personal toolbar changes.

2- UNINSTALL FIREFOX AND THEN REINSTALL.

(choose solutions up)

sfzamd said

I Use an Sony xperia Z4 android (7.1.1) tablet for work with a Bluetooth keyboard and mouse. The android version of Firefox is my browser of choice but one quirk that hampers efficiency & productivity is that the new tab '+' button is situated at the right corner of the screen and not adjacent to the last open tab as in the windows or desktop versions. If the new tab button can be relocated right next to the last open tab it would be fantastic. Is there a setting that can be changed at present or if not can that be added soon. Would be the best new feature if its added. Thanks.

The query is regarding the "Android" version not Windows :(. The solution suggested might be applicable to firefox windows application. There is no right click in Android.

It is not possible to move buttons in Firefox for Android.

Is there any web resource where I can add a request for this feature to be included in future builds of Firefox android. Does the Firefox development team accept user requests for new features and if yes could any one direct me to such a web location.