Okay say here is your deck:
Lv5 Oo
Lv2 Uu
Lv3 Bb
Lv1 Xx
Lv4 Yy
Lv8 Zz
Lv7 Aa
Lv2 Cc
Lv7 Nn
Lv9 Pp
Lv3 Dd
Lv1 Tt
Lv5 Mm
Lv8 Rr
Lv2 Ee
Lv6 Ff
So the cards that are displayed are: Lv5 Oo, Lv2 Uu, Lv3 Bb, Lv1 Xx, Lv4 Yy, Lv8 Zz
Say you want instead, this order: Lv9 Pp, Lv8 Rr, Lv7 Nn, Lv8 Zz, Lv7 Aa, Lv1 Tt
Okay then find the cards you want to switch and sell and rebuy them like this:
Step 1) sell Lvl5 Oo, sell Lvl9 Pp, buy Lvl5 Oo, buy Lvl9 Pp
Step 2) sell Lvl2 Uu, sell Lvl8 Rr, buy Lvl2 Uu, buy Lvl8 Rr
Step 3) sell Lvl3 Bb, sell Lvl7 Nn, buy Lvl3 Bb, buy Lvl7 Nn
Step 4) sell Lvl1 Xx, sell Lvl1 Tt, buy Lvl1 Xx, buy Lvl1 Tt
Step 5) sell Lvl4 Yy, sell Lvl7 Aa, buy Lvl4 Yy, buy Lvl7 Aa
Now you probably have this order: Lv9 Pp, Lv8 Rr, Lv7 Nn, Lv1 Tt, Lv7 Aa, Lv8 Zz
You can rearrange within your top 6 too.
Step 6) sell Lv1 Tt, sell Lv8 Zz, buy Lv1 Tt, buy Lv8 Zz
and you should have the correct order. ^^ Of course, you just have to apply the same pattern to any 2 cards you want to switch. You can only switch 2 cards at a time- although there should be a way to switch more than 2 at a time, this method keeps it simple and consistent and leaves less room for error. ^^