When working with ProStructures elements it is always best to turn on the ProStructures snaps. This wiki explains how to activate the ProStructures snaps.
1. Open the Global Settings or Options by holding the right mouse button in the View window and then click on the Options. Or search ‘Global Settings’ in the Search Ribbon and click on it to open it.
2. Left-click on the Snaps page and set the settings as shown in the below image. ProStructures Snaps, ProStructures Legacy Snaps and ProStructures Tooltip can also be enabled or disabled from the PS Toggles.
Now for the snaps you have following three options.