Video of the supposed problem:

https://mf-md.com/owncloud/index.php/s/dcV1COkar42dJnS
Maybe it's just that I dont know howto ..

Hmm, not sure but it looked like you had the composition selected and not the video clip

It is just how compositions work, if they have no track to refer to, they basically don't do anything, and since you have nothing on track one in that first part, the size is not changing. You can just use an effect for the result you want

Arkengheist wrote:It is just how compositions work, if they have no track to refer to, they basically don't do anything, and since you have nothing on track one in that first part, the size is not changing. You can just use an effect for the result you want

Good catch! Even though the track reference was set to "automatic" there was indeed no clip on V1 so nothing for kdenlive to interact with.