Can someone show me how to setup vendor check alignment with QB online plus?

I can show you how to align your vendor's check, @info840. 

First, make sure to have the latest version of Adobe Reader. Then, set it as the default PDF viewer for your browser. 

If this doesn’t work, proceed with the Fine-tune alignment. 

Here’s how: 

1. Go back to the Print checks setup window.
2. Click the No, continue setup button at the bottom right twice until you get to the Fine-tune alignment page.
3. Adjust the format by dragging the grid inside the large square to the place where it appears on your printout.
4. Select View preview and print sample in the lower left, and choose Print icon at the top right.
5. Click Finish Setup when the alignment is already fine.

Check this article for more information: Align how your checks print. Here's also more information on how to adjust or check the printing alignment for all sales forms: Print sales forms. 

Let me know if there's anything that I can assist in printing your checks. I'm always here to assist.