This is an Archlinux user's guide. Have you tried Manjaro guides or tutorials?
If not, please undo your previous changes and choose one Optimus method, while you should read more on troubleshooting video drivers.
There are several options for hybrid Nvidia graphics, each with their benefits and drawbacks.
These options are:
bumblebee (render offload)
-- performance not great (some overhad)
(from arch wiki below: "Bumblebee not only has significant performance issues  , but also has no plans to support Vulkan ") (*)
-- preconfigured, ability to use nvidia gpu “ondemand” with primusrun command
-- development seem…
It is not necessary to change anything if you don't encounter serious display problems, or your applications run successfully.
If you believe there is a need to change the video driver or the current configuration, first try to find evidence that there is something wrong. Read the Troubleshooting section bellow.
Also make sure you have your system packages properly updated.
If you decide to change the video driver, prepare for.. the worst, before you find yourself in front of a …
After any errors occur, please post info, as suggested in 2nd tutorial.