​@Hanna Kotlarowa If by “see” you mean they cannot find the Timer app to start it, this is expected if they are accessing the board as Visitors (i.e., Anyone with the link):

Source: https://help.miro.com/hc/en-us/articles/360017730933-Timer

Or, if you meant “You started a timer and they cannot see it”, they should be able to. I just tested this and even as a non-registered user (i.e., again, using the Anyone with the link - even as a viewer) and the running Timer was present.

This article explains who will have access to the Timer app to start a timer:

https://help.miro.com/hc/en-us/articles/7045408248594-Visitors-guests-and-members#h_01J9PHAD59MB28HHNFC6NDBPQ4