Try using the y_position argument of geom_signif
library(ggplot2)
library(ggsignif)
#> Warning: package 'ggsignif' was built under R version 3.5.3
GF4 <- read.csv("c:/users/fxcampos/Documents/R/Play/GF4.csv")
ggplot(GF4, aes(Tache, value,))+
geom_dotplot(binaxis = "y", dotsize= .01)+
geom_jitter(position=position_jitter())+
geom_boxplot(alpha= 0.5)+
geom_signif(comparisons = split(t(combn(levels(GF4$Tache), 2)), seq(nrow(t(combn(levels(GF4$Tache), 2))))),
map_signif_level = TRUE, step_increase=.06, y_position = c(5:10))+
theme_classic()+
ggtitle("Gyrus Fusiform 4")+
labs(y="Y")+
labs(x="X")
#> `stat_bindot()` using `bins = 30`. Pick better value with `binwidth`.
#> Warning: Removed 8 rows containing non-finite values (stat_bindot).
#> Warning: Removed 8 rows containing non-finite values (stat_boxplot).
#> Warning: Removed 8 rows containing non-finite values (stat_signif).
#> Warning: Removed 8 rows containing missing values (geom_point).

Created on 2019-05-25 by the reprex package (v0.2.1)