title: How to change system language in RStudio?
body: <p>I change my system language to English both:<br>
  1) In R, R console: language = en<br>
  2) For any R script file : Sys.setlocale(category = "LC_ALL", locale = "english")<br>
  But when I started a new R markdown file in R Studio, the date is still not in English.<br>
  Anyone can help solve this issue? Thank you.  </p>
  
  <p>Updated with sessionInfo()  </p>
  
  <pre><code>R version 3.4.4 (2018-03-15)
  Platform: x86_64-w64-mingw32/x64 (64-bit)
  Running under: Windows 7 x64 (build 7601) Service Pack 1
  
  Matrix products: default
  
  locale:
  [1] LC_COLLATE=English_United States.1252  LC_CTYPE=English_United States.1252   
  [3] LC_MONETARY=English_United States.1252 LC_NUMERIC=C                          
  [5] LC_TIME=English_United States.1252    
  
  attached base packages:
  [1] stats     graphics  grDevices utils     datasets  methods   base     
  
  other attached packages:
  [1] tmaptools_1.2-3        tmap_1.11-1            countrycode_1.00.0    
  etc. 26 packages attached            
  
  loaded via a namespace (and not attached):
  [1] readxl_1.0.0       backports_1.1.2    osmar_1.1-7        plyr_1.8.4         lazyeval_0.2.1    
  etc. 114 loaded via a namespace
  </code></pre>