Rename Matrix Column Instead of its Default in R - r

Question

I have an R function which I rewrite to give room for foreach function and parallel process but the matrix result is having a different column name.
The original function below:
# simulate arima(1,0,0)
library(forecast)
n=10
phi <- 0.6
set.seed(106100125)
ar1 <- arima.sim(n, model = list(ar=phi, order = c(1, 0, 0)), sd = 1)
auto.arima(ar1)
ts <- ar1
t <- length(ts) # the length of the time series
li <- seq(n-2)+1 # vector of block sizes to be 1 < l < n (i.e to be between 1 and n exclusively)
# vector to store block means
RMSEblk <- matrix(nrow = 1, ncol = length(li))
colnames(RMSEblk) <-li
for (b in 1:length(li)){
l <- li[b]# block size
m <- ceiling(t / l) # number of blocks
blk <- split(ts, rep(1:m, each=l, length.out = t)) # divides the series into blocks
# initialize vector to receive result from for loop
singleblock <- vector()
for(i in 1:10){
res<-sample(blk, replace=T, 10) # resamples the blocks
res.unlist<-unlist(res, use.names = F) # unlist the bootstrap series
# Split the series into train and test set
train <- head(res.unlist, round(length(res.unlist) * 0.6))
h <- length(res.unlist) - length(train)
test <- tail(res.unlist, h)
# Forecast for train set
model <- auto.arima(train)
future <- forecast(test, model=model,h=h)
nfuture <- as.numeric(future$mean) # makes the `future` object a vector
RMSE <- rmse(test, nfuture) # use the `rmse` function from `Metrics` package
singleblock[i] <- RMSE # Assign RMSE value to final result vector element I
}
RMSEblk[b] <- mean(singleblock) # store into matrix
}
RMSEblk
The Desired Arrangement of Result
## 2 3 4 5 6 7 8 9
##[1,] 1.022961 1.440676 1.54268 1.074976 1.205165 1.186345 1.436563 1.501218
The modified function
## Load packages and prepare multicore process
library(forecast)
library(future.apply)
plan(multisession)
library(parallel)
library(foreach)
library(doParallel)
n_cores <- detectCores()
cl <- makeCluster(n_cores)
registerDoParallel(cores = detectCores())
#########################################################
## simulate ARIMA(1,0, 0)
n=10
phi <- 0.6
set.seed(106100125)
ar1 <- arima.sim(n, model = list(ar=phi, order = c(1, 0, 0)), sd = 1)
auto.arima(ar1)
ts <- ar1
########################################################
## greate a vector of block sizes
t <- length(ts) # the length of the time series
li <- seq(n-2)+1 # vector of block sizes to be 1 < l < n (i.e to be between 1 and n exclusively)
########################################################
## This section create matrix to store block means
RMSEblk <- matrix(nrow = 1, ncol = length(li))
colnames(RMSEblk) <-li
########################################################
## This section use foreach function to do detail in the brace
RMSEblk <- foreach(b = 1:length(li), .combine = 'cbind') %do%{
#for (b in 1:length(li)){
l <- li[b]# block size
m <- ceiling(t / l) # number of blocks
blk <- split(ts, rep(1:m, each=l, length.out = t)) # divides the series into blocks
######################################################
## Thissubsection initialize vector to receive result from for loop
singleblock <- vector()
singleblock <- foreach(i = 1:10, .packages = c("forecast"), .combine = 'c') %dopar% { ### Replacement parallel foreach loop
#for(i in 1:10){
res<-sample(blk, replace=T, 10) # resamples the blocks
res.unlist <- unlist(res, use.names = FALSE) # unlist the bootstrap series
train <- head(res.unlist, round(length(res.unlist) * 0.8)) # Train set
test <- tail(res.unlist, length(res.unlist) - length(train)) # Test set
nfuture <- forecast(train, model = auto.arima(train), lambda=0, biasadj=TRUE, h = length(test))$mean # makes the `forecast of test set
RMSE <- accuracy(nfuture, test) # RETURN RMSE
singleblock[i] <- RMSE # Assign RMSE value to final result vector element I
}
RMSEblk[b] <- mean(singleblock) # store into matrix
}
stopCluster(cl)
RMSEblk[] <- future_vapply(b=1:length(li), RMSEblk[b], numeric(1))
RMSEblk
** The Undesired Arrangement of Result**
## Error: ‘is.function(FUN)’ is not TRUE
##>
##> RMSEblk
##result.1 result.2 result.3 result.4 result.5 result.6 result.7 result.8
##[1,] 34.4202 20.54789 24.77103 25.49809 15.42677 30.80389 18.28471 15.92572
What I want
I want the result of the second function to be presented and arranged as the result of the first function. That means instead of result.1 I want 2 as the column name or instead of result. 8 I want 9 as the column name of function 2.