Eventually I used this script, fished from the other forum
I modified it slightly to account for the fact that I have three classes for the dimensions (so I have three scripts at the end by just modifying C1).
It gives this:
Procedure SwapDimsAutoClass;
{©2023 Pat Stanford - pat@coviana.com}
{licensed under the Boost Software License 1.0}
{https://github.com/boostorg/boost/blob/master/LICENSE_1_0.txt}
{TL/DR Use as you want, attribution for source, No warranty}
{With great thanks the Raymond Mullin (@MullinRJ) for help in}
{identifying the proper Preference code.}
CONST C1='Cotations';
VAR H1 :Handle;
L1,L2,L3 :LongInt;
N1 :Integer;
R1 :Real;
S1 :String;
BEGIN
S1:=Index2Name(GetPrefLongInt(546));
BEGIN
SetPrefLongInt(546,Name2Index(C1));
End
End;
Run(SwapDimsAutoClass);
THANK YOU all !