Fixed location on toolbar

on my tool bar i have the drive buttons (both fixed and removable) on the left and a bunch of custom buttons to the right of the drive buttons
machine1 has 3 or 4 drives but machine2 has 6 or 7 drives so the result is that the custom buttons slide to the right on machine2 (they still fit)
how can i pin down the leftmost custom button to a fixed location? i navigate geographically and it is is disconcerting to see them in different locations
is there something like a spacer that will allocate space and stay put ?

You can add a spacer by right clicking on the toolbar and choosing New Spacer. Spacers can either be fixed width or full width. Full width ones use the extra space, so anything after them will be aligned to the right, or in the middle if you have another full width spacer farther to the right (they share out the extra space).

it worked! thank you