My RStudio (V 0.99.491) is inept to change the R Version.
I act in the ordinary way through Global Options --> R-Version. Afterwards it hangs and doesn't work or react any more. The initial version of R which works fine is R 3.1.0. I have never had such a problem before. Maybe someone has faced with a similar problem.
I tried to uninstall RStudio, and install it again, but this hasn't help to fix the issue.