Get an installed program of Joyoshare Media Cutter started on your computer. Then directly drag and drop an MP4 file to the area you follow. It's handy to alternatively select a video from local folder to add by pressing the "Open" option.
This program loads MP4 video soon and by default plays it. You can now click on "Format" option to select "Encoding mode". Then head to "General Video" to choose MP4. The gear icon located at the top right corner of it enables you to set resolution to 240*160, 320*240, 480*320, 640*360, 720*480, 1920*1080 and more. It's practical to configure other parameters if you need.
Go back to the main interface and find "Edit"
button. In the pop-up window, go for Adjust > Aspect Ratio to choose "16:9", "4:3", "Full Screen", "Pan Scan", "Original Display" or "Original Resolution". Therefore, your MP4 size can be changed and better viewed in its optimal presentation.
Edit your MP4 video file to make it more professional. If not, you are able to click on Start option on the main interface to output it. Next, press on the button - "Open The Output Folder", to have a check.