[ubuntu] boot sequence mac/ ubuntu

Hy everybody,

I just installed Ubuntu 20.04 in dual boot on my iMac 27" mid 2011 (Mac OS High Sierra). But now it always automatically starts up in Ubuntu, unless I hit my option key, then I can choose between Ubuntu en Mac OS. Is het possible one way or the other to get that choice every time I power up my iMac without pushing that option key?

Many thanks for your answers!



Jan.