Sometimes when you have to change from one chord fingering to another your fingers get tied up. Here are a couple of things you can try: 1) Find one or more pivot note(s)/finger(s). That is, one note may remain the same between the two chords. Try to keep that finger down and move the rest. For example: 1st position B7 to E. 2nd finger on 2nd fret A string (note = b). 1st position C to Am, 2nd finger on 2nd fret D string (note = e) and 1st finger 1st fret B string (note = c) all you need to move is your 3rd finger. You may want to try different fingerings to find a pivot finger. 2) Although it's best to place all fingers at once, sometimes for really tricky changes you need to compromise. In that case, finger the first note to be hit first. Then place the others. In most strums, that means the lower note in downstroke or highest in upstroke. In some styles it could be any note. A great way to practice switching chords. Lightly place your fingers in position for the first chord but DO NOT PRESS DOWN! Get them as well positioned as possible arched over the strings on the fingertips. Now slowly and smoothly move your fingers to the next chord in the sequence. DO NOT PRESS DOWN. Slowly and smoothly go back to the previous chord but do not press. Do this over and over from chord 1 to chord 2 and back to chord 1 without using any pressure. Once you can do it smoothly and rapidly then practice going back and forth while pressing the strings. Do the pressing method slowly, make sure that you can hear every note when you play the chords then speed it up. You will be amazed at how quickly you will master the fingerings by not pressing. This really works well for the beginner as well as the more advanced player.