Playing Smoothly
Playing Smoothly is, in fancy musical terms, often called "legato". Essentially, this means to play in a flowing manner without noticeable breaks between notes. This takes practice on any instrument but is particularly difficult on the Mountain Dulcimer. The Mountain Dulcimer has only 3 strings. As soon as you lift your finger off a sting you stop the string ringing at the right note. Also, moving your fingers in any way while they are fretting a note will affect the sound the dulcimer is making.
Practice being precise in your fretting hand movements to progress in your joyful journey of playing the mt dulcimer.
Some things to help smooth out your playing:
Play on your fingertips just like you do when typing on a keyboard (don't use the pads of your fingers)
This requires very short finger nails on your fretting hand.
Keep you fingers hovering above the fret board (don't lift your hand or fingers up to high)
Be intentional with every movement of your fretting hand.
Use precise and quick changes from one fretting position to the next.
Keep your fretting arm at a comfortable angle with your wrist straight and free to move.
Keep you dulcimer in a position so that it is easy to reach the higher frets.
This often requires a strap to have the dulcimer angled off and away from you on your fretting hand side.
Choose fingering patterns that allow at least one finger to be available to fret the next note/chord.
Once you have figured out the best fingers to use for your hands, practice the tricky transitions over and over again to get those in your muscle memory.
Here are some good instructional videos about playing more smoothly ...
Legato Fretting Techniques - Guy Babusek
Multi-Finger Playing - Bing Futch
Finger Placement - Brett Ridgeway