When I subset a seurat object and start to reanalyze it, I can't change the number of variable features from the older (bigger object).

seuObj
An object of class Seurat 
26379 features across 56411 samples within 1 assay 
Active assay: RNA (26379 features, 2000 variable features)
 3 layers present: data, counts, scale.data
 3 dimensional reductions calculated: pca, umap, tsne

After subsetting and cleaning the object, I re-do also the normalization and finding the variable features, but it stays at 2000, even though I can see in the plot, that I have a lot more.

export <- subset(x = seuObj, idents = c(1,2,11) )
export <- NormalizeData(export, normalization.method  ="LogNormalize", scale.factor = 10000) 
export <- FindVariableFeatures(export, selection.method = "mean.var.plot", mean.cutoff = c(0.0125, 3), dispersion.cutoff = c(0.5, Inf))

export
An object of class Seurat 
26379 features across 13384 samples within 1 assay 
Active assay: RNA (26379 features, 2000 variable features)
 2 layers present: counts, data

How can I reset (change)this value?