Hi. I am currently interested in this particular project on Wolfram Demonstrations Project: http://demonstrations.wolfram.com/MagneticForceOnASlidingBar/

I wanted to simulate the change of more than one parameters simultaneously, while keeping the rest as it is. I am thinking of a button to choose what parameters are to be manipulated automatically, but I don't know how can I do that.

Kindly asking a help, or maybe a suggestion for other method. Thank you very much.

Source code:

Manipulate[
 With[{m = .05, \[ScriptL] = .3, i = 1}, 
  Graphics[{Line[{{0, 0}, {0, .4}}], Line[{{0, .575}, {0, 1}}], Brown,
     Line[{{0, .4}, {-.05, .425}, {.05, .45}, {-.05, .475}, {.05, \
.5}, {-.05, .525}, {.05, .55}, {0, .575}}], Yellow, Thickness[.03], 
    Line[{{0, 0}, {2, 0}}], Line[{{0, 1}, {2, 1}}], Green, 
    Translate[{Line[{{0, -.1}, {0, 1.1}}], Thickness[.01], Orange, 
      Arrow[{{0, .5}, {-i \[ScriptL] B, .5}}], Blue, 
      Arrow[{{0, .5}, {vi Exp[-t/(m R/(B^2 \[ScriptL]^2))], .5}}]}, \
{-vi (m R/(B^2 \[ScriptL]^2)) (Exp[-t/(m R/(B^2 \[ScriptL]^2))] - 
         Exp[-0/(m R/(B^2 \[ScriptL]^2))]) , 0}], Gray, 
    Table[Inset["\[Times]", {x, y}], {x, -.3, 2, .2}, {y, 0, 1, .2}]},
    PlotRange -> {{-.35, 2}, {-.2, 1.2}}, ImageSize -> 500, 
   PlotLabel -> 
    Row[{Style["v", Italic], " = ", 
      NumberForm[
       vi Exp[-t/(m R/(B^2 \[ScriptL]^2))], {5, 3}]}]]], {{t, .8, 
   Style["t", Italic]}, 0, 1, 
  Appearance -> "Labeled"}, {{vi, .6, 
   Subscript[Style["v", Italic], "0"]}, 0, 1, 
  Appearance -> "Labeled"}, {{R, 50, Style["R", Italic] }, 0.01, 100, 
  Appearance -> "Labeled"}, {{B, .7, Style["B", Italic]}, 0.01, 1., 
  Appearance -> "Labeled"}]

Code obtained from http://demonstrations.wolfram.com/versions/source.jsp?id=MagneticForceOnASlidingBar&version=0007