You can’t really change the algorithm in a preset – it would make no sense as the settings would be all wrong.

What you can do is to create a new preset based on the algorithm of your choice.

You don’t say what stompbox you are using, so I can’t give further information. Please read the User Manual for details.

Sorry. I’m using Eventide Space. i think something is wrong. but i can´t explain this in detail. 

The manual says – “You can access Space’s 12 algorithms using the encoder. Simply press and release the encoder…   Turn the encoder to scroll the 12 algorithms. When you stop scrolling the displayed algorithm will load. After a few seconds of inactivity, the algorithm led will turn off and space will revert to normasl preset or play mode” 

I think that i used “quasar” preset with “room” algorithm (Shimmer is default)

Am i confused ? is that possible?