If you're a little stiff in the finger joints, and sometimes find that when you double click to open something it doesn't work, you may need to decrease the speed that Windows interprets as your 'double click'.

Let me explain ...

There is a designated time interval that Windows uses to distinguish between two successive single clicks and a double click.

Anything faster than the designated setting is deemed a double click; anything slower is handled as two single clicks.

In other words, if you allow too long an interval between the 'double click' action, Windows assumes you've carried out two single clicks.
You can change the time interval by visiting the Control Panel and double clicking the Mouse icon. Things will be self-evident when you get there...

Start, Settings, Control panel, Mouse icon, Adjust 'Double Click speed.

Mousing around can be fun sometimes