my scroll bar shows up and then immediately disappears. How can I get the scroll bar back ?

I have the same problem. I think it's been there since the major upgrade to mSecure on the Mac. - quite a while.

Im addition to the characteristics Joseph describes:

• I have System Preferences set to always show the scroll bar, but it only appears momentarily when clicking on an entry at the to or bottom of the list of entries and moving the selection with the down (or up) arrows so the list scrolls. However the scroll bar disappears so quickly, I can't grab its with the mouse. 
  
• With mSecure open, if I change the macOS scroll preference to something other than always on and the immediately back again, the vertical scroll bar appears and operates correctly.
• However if in this state, if I use the mouse to select a category from the left hand panel, the scroll bar immediately disappears.
• If I drag the bottom of the window up or down, the scroll bar reappears momentarily, just long enough for me to grab it. But the appearance of the scroll bar is different. There is no bar. In it's place, just a black object which one can drag up and down to scroll.
• With the scroll bar in place by changing the system preference back and forth, If I click in the left hand panel, the scroll bar disappears.
• If I get the scroll bar to appear by changing the system preference back and forth and the quit and restart mSecure, the scroll bar is gone again.

Yes, anytime something has been changed I will always shut down and restart. Same thing happens. The scroll bar does show up for a brief moment and then disappears. The only way I can check a password is to input the name at the top of the page and it then shows up. Obviously the scroll bar would help. Do you think it has anything to do with the mouse itself ?

Eden- Based on your instruction I first checked  and found the setting on "when scrolling". I then switched to "always" and it initially worked. A short time later I went back on and the scroll bar stayed on for less than a second and disappeared (as before). Since then I've also tried the "automatically based on mouse or trackpad" and the same thing occurs, the scroll bar shows up and then disappears. None of my other programs have that issue.  

It worked initially and the scroll bar appeared. Then it disappeared again, same as before. Are you suggesting it's an Apple problem and not an mSecure issue ?

Version 5.5.3 on Apple. On my lap top the scroll bar first appears then immediately disappears. I appreciate whatever help you can provide.