Advice with toddler trying to poo..

My nearly 3 year old has mastered the toilet for wee and now only has the odd accident but we are really struggling with the poo situation. I can tell when she needs it as she’s straining so we go to the toilet this happens about 4/5 times a day where it’s just tmi either wet farts or she’s not managed to go yet so it’s just skid marks or some poo in her pants. She eventually goes in the evening most of the time after having this for most of the day. we’ve tried staying on the toilet longer etc but I’m really not sure what else to do now…