Start Menu Frustrations.

[Trouble]

Well it took me a while and now I'm just feeling dumb.
Your ability to resize the start menu on Windows 10 (especially horizontally) is dictated by your overall monitor size and the resolution you are using. AND....
Dragging the right border to the right sometimes doesn't seem to look like it's working until to move it far enough to the right.
Over all it should support approximately 75% of your overall available screen and in my opinion really enhances the usability of the new Start Menu.
You can go from this....

To this......

And use the title bar to drag the groups where ever you want to place them.
It may be that it results in a lot of wasted space but for those who like that sort of thing it does provide a more readily available source for quickly accessing your programs, than scrolling through the never ending "All Apps" menu.

I just feel kinda dumb that it took me this long to figure out how it actually works.

 

[averageguy]

It takes no more than 10 seconds to stretch the screen. All you had to do was to go to setting, personalization, and then turn on start screen. It automatically, adjusts the resolution, and covers your entire screen. Has nothing to do with the size of the monitor of the computer.

 

[clifford_cooley]

"Resolution vs size of the monitor"

I do believe you are Nitpicking and making an issue that wasn't meant to be taken that way.

 

[Trouble]

All you had to do was to go to setting, personalization, and then turn on start screen

That would work fine if I wanted a start menu that covered my whole screen but I didn't.