Try

USE myrep.frx
GO TOP

lcCrLf = CHR(13)+CHR(10)
lcNewPS = "5"

lcPS = STREXTRACT(expr, "PAPERSIZE", lcCrLf,1,1+4)
REPLACE Expr WITH STRTRAN(Expr, lcPS, "PAPERSIZE=" + lcNewPS + lcCrLf)

USE

>
> Could you give me some advice on how to update a memo field in frx report file? I want to update the papersize in Expr fields.Thank you!