Language change?

Im just with my language and i cant change it

i cant even use slow motion HELP???

Click Settings> Language, then select a language.

As far as slow motion someone has a tutorial on YouTube.

after i changed the language it still stayed there and i cant still use the speed bar

Try to reinstall.
Which system?

For Speed, you might be affected by this bug:

I have not been able to get the help yet. This might take a long time until someone who is a developer and affected by this bug volunteers to make a fix.