I expect the levels are being arranged alphabetically. You can impose a certain order using the factor() function.
DF <- data.frame(Subj = c("Zoo", "All", "Accidental", "0-4", "10-15", "5-9"),
Value = 1:6)
DF
#> Subj Value
#> 1 Zoo 1
#> 2 All 2
#> 3 Accidental 3
#> 4 0-4 4
#> 5 10-15 5
#> 6 5-9 6
library(dplyr, warn.conflicts = FALSE)
DF <- arrange(DF, Subj) #sort by Subj
DF
#> Subj Value
#> 1 0-4 4
#> 2 10-15 5
#> 3 5-9 6
#> 4 Accidental 3
#> 5 All 2
#> 6 Zoo 1
#set the order of the factor levels in Subj
DF$Subj <- factor(DF$Subj, levels = c("All", "Zoo", "Accidental", "0-4", "5-9", "10-15"))
DF <- arrange(DF, Subj) #sort by Subj
DF
#> Subj Value
#> 1 All 2
#> 2 Zoo 1
#> 3 Accidental 3
#> 4 0-4 4
#> 5 5-9 6
#> 6 10-15 5
Created on 2020-08-04 by the reprex package (v0.3.0)